Question

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

Answer 1

`3/14 gallon` of `90%` vinegar to be added to get `20%` vinegar.

Explanation:

Let `x` gallons of `90%` vinegar is added to get `20%`vinegar.

Then by given condition , #1*5/100 + x*90/100= (1+x)*20/100 or 1/20+ 9/10x = 1/5 + 1/5x
or 9/10x - 1/5x = 1/5-1/20 or 7/10x=3/20 or x = (10*3)/(7*20)= 3/14 gallon #

`3/14 gallon` of `90%` vinegar to be added to get `20%`vinegar.[Ans]