Question

How much 90 percent vinegar do you have to add to a gallon of 5 percent vinegar to get 20 percent vinegar?

Hint: You want the final percentage of pure vinegar to be 20%. You have 1+x gallons of fluid where x is the number of gallons you add. Think about how much pure vinegar is in those 1+x gallons.

Answer 1

@Directrix

Answer 2

From: @stankytukus

0.90x + 0.05*1 = 0.20(x+1) where x is the amount of 90% vinegar

Multply through by 100

90x + 5 = 20x + 20

70x = 15

@stankytukus requests that you solve for x @Pulsified333

Answer 3

x=15/70?

Answer 4

Yes. And, as a decimal, how many gallons is that?

Answer 5

0.214285714

Answer 6

Check to see if your answer has to be given to a nearest decimal place.

The exact answer is 15/70 which equals 3/14 after dividing out the common factor.

Answer 7

it is correct :D

Answer 8

Good to hear.