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### Course: Math (NSDC) - English>Unit 6

Lesson 4: Finding percentages

# Percent word problem: guavas

We're putting a little algebra to work to find the full price when you know the discount price in this percent word problem. Created by Sal Khan.

## Want to join the conversation?

• When he talks about fractions it confuses me.
• I definitely agree with you i draged this out because i was forced to
• what is a Guava?
• Guavas ae a type of fruit that can be pink or white from the inside. They have a sweet taste and a hard green skin.
• i did something slightly different that i think is good, but I didn't got the right answer. so if someone could help me, it would be really great. So this is what i did:
-too find the price of each guavas (with 30% off), i divided 12,60 by 6 and i got 2,10\$ each guava with 30% off
-Then i did 30% of 2,10\$, which gave me 0,63. So i add 2,10 with 0,63 which gave me 2,73\$. So each guava WITHOUT 30% off (full price) is equal to 2,73\$.
-Finally i did 2,73% x 2 = 5,46\$ total
BUT i didn't got the right answer and i don't know why!
if someone find my mistake and tell me where it is, i would be really grateful for them!
• The amount by which the regular price exceeds the sale price is not 30% of the sale price, but instead is 30% of the regular price!

So you can’t just add 30% of \$2.10, to \$2.10, to get a regular price of \$2.73 per guava...this is a very common type of mistake students make with this type of problem.

Instead, you would need to divide \$2.10 by 0.7 to get a regular price of \$3 per guava, since the sale price is 100%-30%=70% of the regular price.
• let x represent the price of 1 guava fruit.
6x - 6x * 0.30 = 12.60
6x - 1.8x = 12.60
4.2x = 12.60
x = 3
• Yes, you've done it perfectly. Sal did the same thing, except for the first step. He took x as the price of 6 guava fruits.
• This was so confusing and no help
• The first thing that you need to do is to write the equation. So here are the steps:
1.Define the variable x :
x = cost of 6 guavas at full price.
2 We know that today, there is a 30% off on guava. So we subtract:
x - 0.3x
3. It says that the discounted price for 6 guavas is \$12.6.
So we can finish the equation:
1x - 0.30 x = 12.6
Second, we must solve the equation.
1.Simplify. We see that 1x and 0.30 x both have a x. But how to simplify? 1 of something minus 0.30 of something is 0.70 of something. So:
1x- 0.30x = 0.70x.
0.70x = 12.6
2. Get rid of the number on the left-hand side. How? We can divide. But if we divide 0.70 on the left-hand side, we must also divide 0.70 on the right-hand side.
0.70x/0.70 = 12.6/0.70
x = 18.
I hope it helps!
(PS. If you do not know why to divide the same thing on both sides, you can watch the videos about the introduction of equations.)
• This is confusing, I don't understand percentages world problems. I SO confused.
• I still don't understand how he got 0.70 by subtracting 0.30 by 1X,I believe my problem is that I didn't understand what 1X was.
• Look at it this way: The regular price is x. The sale price is 30% off the regular price, so the sale price would be x - 0.3x. Now isolate the variable. The variable x is the same thing as saying 1 times x, or 1x. If you take 30% off 1x, then 70% would remain. This means that the sale price of 6 guavas (\$12.60) is only 70% of the full price, which means that 12.60 = 0.7x. Since 0.7 and x are being multiplied, and we need to find the value of 6, you have to do 12.60 divided by 0.7 to get 18 dollars as the full price, and then you'd have to do 18 / 6 = 3 to get the unit price of each guava. Finally, you do 3 x 2 = 6, so 2 guavas would cost \$6 at the regular price (no tax included).

I hope this helps!
• whats a guava?
• A guava is a type of tropical fruit that is pear/avacado-shaped on the outside, but watermelon/cantalope-like on the inside. The inside can either be pink or white. The outside, or rind, is green.