how do i solve if 8 is 90% of n

Change 90% into a decimal: 0.90 or 0.9 Translate the key words: "of" = multiply and "is" means "=" Translate the phrase: "8 is 90% of n" becomes 8 = 0.90n Solve for "n" by dividing both sides by 0.9 Alternatively, set up a proportion: 8/n = 90/100 Cross multiply and divide to solve for "n" Hope this helps.

Why is X the most used variable is it because of the x and y axis or some other reason

yes, it is! x and y are commonly used as variables on khan, but what they are most famous for is the the x and y axis, but as sal says "You can use any variable but were going to use x and y" they just use it on khan for equations and other math problems often! btw off topic, im a fellow programmer two! nice to meet you!:D

If t=11, what is the answer?

expression: 5t+3 If t=11: (5x11)+3 =55+3 =58 Hope this helps!

At 0:41, is 5. (1) not the same as 5 x x 1 ?

If another operation is before the parentheses, then you don't multiply. If you have something like 3- (-3), you just subtract the -3. If yo have 4*(5), you only multiply once.

hey guys i just started algebra any tricks becaus this is hard

Yeah, i think that you should try learning simplfying and one step equations first. They are easy because it is what you know just in a basic form. work from there and you will get a basic understanding of algerbra and be able to work forward and go to harder stuff.

So is evaluating expressions is like you have a variable that stands for a number so you figure out what the value of the variable is first isolate the variable then do the inverse operation?

Yes, because if you want to isolate the variable in 3+X=7, you could do 3-3+X=7-3, and the 3 and 3 cancel out.

Does the letter stand for something in each problem?

Yes, it stands for the variable’s value.

For these types of problems, you are given an algebraic expression and a value for the variable. 1) Replace (substitute) variable in the expression with its given value. You then have a basic math problem to simplify. 2) Follow order of operations rules (PEMDAS) to simplify the problem. Hope this helps.

How do you do 2(x-7)=4(x-4)

1) Distribute 2 and 4 to eliminate the parentheses: `2x - 14 = 4x - 16` 2) Subtract one of the X terms from both sides. You can pick either one. Let's say you subtract 2x from both sides (this may be a little easier to work with a positive value as a result). `- 14 = 2x - 16` 3) To isolate the remaining X term, you need to add 16 to both sides: `2 = 2x` 4) Then, complete the problem by dividing both sides by 2. `1 = x` Hope this helps.

Main content

Grade 7 (Virginia)

Course: Grade 7 (Virginia) > Unit 2

Lesson 1: Substitution & evaluating expressions

Evaluating an expression with one variable

Name: Evaluating an expression with one variable
Uploaded: 2011-02-20T16:40:17Z
Description: In this math lesson, we explore the expression 5t+35t+35, t, plus, 3 to calculate the cost of participating in a hospital raffle fundraiser. By evaluating the expression for different values of t, the number of tickets purchased, we find the costs for buying 1, 8, and 10 tickets, which are 8, 43, and 53 dollars, respectively.

Google Classroom

In this math lesson, we explore the expression 5t+35t+35, t, plus, 3 to calculate the cost of participating in a hospital raffle fundraiser. By evaluating the expression for different values of t, the number of tickets purchased, we find the costs for buying 1, 8, and 10 tickets, which are 8, 43, and 53 dollars, respectively. Created by Sal Khan and Monterey Institute for Technology and Education.

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Zane( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)
Posted 3 years ago. Direct link to Zane( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)( ͡° ͜ʖ ͡°)'s post “how do i solve if 8 is 90...”
how do i solve if 8 is 90% of n
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(11 votes)
Answer
- Kim Seidel
  Posted 3 years ago. Direct link to Kim Seidel's post “Change 90% into a decimal...”
  Change 90% into a decimal: 0.90 or 0.9
  Translate the key words: "of" = multiply and "is" means "="
  Translate the phrase: "8 is 90% of n" becomes 8 = 0.90n
  Solve for "n" by dividing both sides by 0.9
  
  Alternatively, set up a proportion:
  8/n = 90/100
  Cross multiply and divide to solve for "n"
  
  Hope this helps.
  Comment on Kim Seidel's post “Change 90% into a decimal...”
  (16 votes)
Suhani
Posted 3 years ago. Direct link to Suhani's post “Why is X the most used va...”
Why is X the most used variable is it because of the x and y axis or some other reason
Button navigates to signup pageComment on Suhani's post “Why is X the most used va...”
(5 votes)
Answer
- 𝘽𝘼𝙏𝙈𝘼𝙉
  Posted 3 years ago. Direct link to 𝘽𝘼𝙏𝙈𝘼𝙉's post “yes, it is! x and y are c...”
  yes, it is! x and y are commonly used as variables on khan, but what they are most famous for is the the x and y axis, but as sal says "You can use any variable but were going to use x and y" they just use it on khan for equations and other math problems often! btw off topic, im a fellow programmer two! nice to meet you!:D
  Comment on 𝘽𝘼𝙏𝙈𝘼𝙉's post “yes, it is! x and y are c...”
  (9 votes)
luke.shultz
Posted 4 months ago. Direct link to luke.shultz's post “why does it look like he ...”
why does it look like he is about to hack the main frame
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- korbin
  Posted 2 months ago. Direct link to korbin's post “frfrfr”
  frfrfr
  Comment on korbin's post “frfrfr”
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Tucker Christiansen
Posted 3 years ago. Direct link to Tucker Christiansen's post “If t=11, what is the answ...”
If t=11, what is the answer?
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(4 votes)
Answer
- Ridhi superr34
  Posted 3 months ago. Direct link to Ridhi superr34's post “expression: 5t+3 If t=11...”
  expression: 5t+3
  
  If t=11:
  
  (5x11)+3
  =55+3
  =58
  
  Hope this helps!
  Button navigates to signup page
  (2 votes)
Darren
Posted 9 years ago. Direct link to Darren's post “At 0:41, is 5. (1) not th...”
At
0:41
, is 5. (1) not the same as 5 x x 1 ?
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(4 votes)
Answer
- N Peterson
  Posted 9 years ago. Direct link to N Peterson's post “If another operation is b...”
  If another operation is before the parentheses, then you don't multiply. If you have something like 3- (-3), you just subtract the -3.
  If yo have 4*(5), you only multiply once.
  Comment on N Peterson's post “If another operation is b...”
  (7 votes)
apoudel11
Posted 2 months ago. Direct link to apoudel11's post “hey guys i just started a...”
hey guys i just started algebra any tricks becaus this is hard
Button navigates to signup pageComment on apoudel11's post “hey guys i just started a...”
(4 votes)
Answer
- Rookychess
  Posted a month ago. Direct link to Rookychess's post “Yeah, i think that you sh...”
  Yeah, i think that you should try learning simplfying and one step equations first. They are easy because it is what you know just in a basic form. work from there and you will get a basic understanding of algerbra and be able to work forward and go to harder stuff.
  Button navigates to signup page
  (4 votes)
LoganL
Posted 2 months ago. Direct link to LoganL's post “This does no thelp.”
This does no thelp.
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(2 votes)
Answer
- Kim Seidel
  Posted 2 months ago. Direct link to Kim Seidel's post “For these types of proble...”
  For these types of problems, you are given an algebraic expression and a value for the variable.
  1) Replace (substitute) variable in the expression with its given value. You then have a basic math problem to simplify.
  2) Follow order of operations rules (PEMDAS) to simplify the problem.
  
  Hope this helps.
  Button navigates to signup page
  (5 votes)
Debra Overman
Posted 6 years ago. Direct link to Debra Overman's post “How do you do 2(x-7)=4(x-...”
How do you do 2(x-7)=4(x-4)
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(2 votes)
Answer
- Kim Seidel
  Posted 6 years ago. Direct link to Kim Seidel's post “1) Distribute 2 and 4 to...”
  1) Distribute 2 and 4 to eliminate the parentheses: 2x - 14 = 4x - 16
  2) Subtract one of the X terms from both sides. You can pick either one. Let's say you subtract 2x from both sides (this may be a little easier to work with a positive value as a result).
  - 14 = 2x - 16
  3) To isolate the remaining X term, you need to add 16 to both sides: 2 = 2x
  4) Then, complete the problem by dividing both sides by 2. 1 = x
  
  Hope this helps.
  Button navigates to signup page
  (4 votes)
cole.bethany
Posted 11 years ago. Direct link to cole.bethany's post “So is evaluating expressi...”
So is evaluating expressions is like you have a variable that stands for a number so you figure out what the value of the variable is first isolate the variable then do the inverse operation?
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(3 votes)
Answer
- Fred Xu
  Posted 4 years ago. Direct link to Fred Xu's post “Yes, because if you want ...”
  Yes, because if you want to isolate the variable in 3+X=7, you could do 3-3+X=7-3, and the 3 and 3 cancel out.
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  (2 votes)
28mkraabe
Posted 8 months ago. Direct link to 28mkraabe's post “Does the letter stand for...”
Does the letter stand for something in each problem?
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- WisteriaGrove
  Posted 4 months ago. Direct link to WisteriaGrove's post “Yes, it stands for the va...”
  Yes, it stands for the variable’s value.
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  (2 votes)

Video transcript

A local hospital is holding a raffle as a fundraiser. The individual cost of participating in the raffle is given by the following expression-- 5t plus 3, or 5 times t plus 3, where t represents the number of tickets someone purchases. Evaluate the expression when t is equal to 1, t is equal to 8, and t is equal to 10. So let's first take the situation where t is equal to 1. Then this expression right over here becomes-- and I'll use that same color-- becomes 5 times 1. 5 times 1 plus 3. 5 times 1 plus 3, and we know from order of operations, you do the multiplication before you do the addition. So this will be 5 times 1 is 5 plus 3, and then this is clearly equal to 8. Now let's do it when t is equal to 8. So when t is equal to 8, this expression becomes-- and I'll do the same colors again-- 5 times 8 plus 3. Same color of green. And once again, 5 times 8 is 40, and then we have the plus 3, there so this is equal to 43. And so we have the last situation, with t is equal to 10. I'll do that in blue. So we have 5 times 10. So 5t is 5 times 10. Instead of a t, put a 10 there. 5 times 10 plus 3. That's a slightly different shade of green, but I think you get the idea. 5 times 10 is 50. We do 50, and then we're going to have to add 3 to that, and that is equal to 53. And we're done.