Question 246553
I don't see how since we are talking about two different mixtures of alcohol.
25% alcohol is x gallons and 35% alcohol is y gallons
x+y=20
x=20-y
y=20-x

.25x+.35*y=.32*20
We have two variables and two equations. 
Substitute EITHER x (x=20-y) or y (y=20-x) in the mixture formula.