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.

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.

What happens if t is a decimal, a logarithmic function or even worse an exponential function?

You get a really complicated problem :D Just do the same thing you would do with a whole number, but if it's an exponential function then simplify the exponent to standard form if you can at the end.

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.

how do i do this with fractions?

The process does not change. You replace the variable with its given value. Then, you follow order of operations rules (PEMDAS) to complete the math. If some numbers are fractions, then you follow the processes for working with fractions. Here's a video that comes a little later in the lessons: https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:foundation-algebra/x2f8bb11595b61c86:substitute-evaluate-expression/v/evaluating-expressions-in-two-variables-with-decimals-and-fractions

why is my life so bad

Only you can answer that question

Main content

Pre-algebra

Course: Pre-algebra > Unit 6

Lesson 2: 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 5 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 5 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 4 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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(12 votes)
Answer
- Kim Seidel
  Posted 4 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...”
  (17 votes)
apoudel11
Posted 6 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...”
(11 votes)
Answer
- Rookychess
  Posted 5 months 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
  (13 votes)
JonathanM
Posted 4 months ago. Direct link to JonathanM's post “why is my life so bad”
why is my life so bad
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- RumiWaffles
  Posted 4 months ago. Direct link to RumiWaffles's post “Only you can answer that ...”
  Only you can answer that question
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  (24 votes)
Ijaz Durrani
Posted 4 months ago. Direct link to Ijaz Durrani's post “What happens if t is a de...”
What happens if t is a decimal, a logarithmic function or even worse an exponential function?
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(6 votes)
Answer
- r3aL1t7
  Posted 3 months ago. Direct link to r3aL1t7's post “You get a really complica...”
  You get a really complicated problem :D Just do the same thing you would do with a whole number, but if it's an exponential function then simplify the exponent to standard form if you can at the end.
  Button navigates to signup page
  (9 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)
Tucker Christiansen
Posted 4 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 7 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
  (3 votes)
luke.shultz
Posted 8 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 6 months ago. Direct link to korbin's post “frfrfr”
  frfrfr
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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)
28levil0148
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how to marh
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- memeixl
  Posted a month ago. Direct link to memeixl's post “do math lessons”
  do math lessons
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Genesis<3
Posted 4 months ago. Direct link to Genesis<3's post “how do i do this with fra...”
how do i do this with fractions?
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(4 votes)
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- Kim Seidel
  Posted 4 months ago. Direct link to Kim Seidel's post “The process does not chan...”
  The process does not change. You replace the variable with its given value. Then, you follow order of operations rules (PEMDAS) to complete the math. If some numbers are fractions, then you follow the processes for working with fractions.
  
  Here's a video that comes a little later in the lessons: https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:foundation-algebra/x2f8bb11595b61c86:substitute-evaluate-expression/v/evaluating-expressions-in-two-variables-with-decimals-and-fractions
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  (4 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.