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

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

%Vinegar = 0.90, 0.05, 0.20 (mix)

Gal Sol'n  = x, 1 gal, x+1=y

Gal Vineg = 0.90x, 0.05(1), 0.20y

 

Solve x+1=y for x; x= y-1 

Plug x into addition of solution

 

0.90(y-1) + 0.05(1) = 0.20y

0.90y - 0.90 + 0.05 = 0.20y

0.90y - 0.20y = 0.85

0.7y = 0.85

y= 1.214 Gal

 

Plug y into x = y-1; x=0.214 Gal

 

You will need 0.214 Gal of 90% Vinegar to make the 20% Solution