Solution X is 80% chemical A and 20% chemical B by volume. Solution Y is 50% chemical A and 50% chemical B by volume. If a mixture of X and Y is 68% chemical A, what percent of the mixture is Solution X?
Options:
A) 20%  B) 25%  C) 30%  D) 35%  E) 40%
The volume of the mixture be X+Y.   0.8X +0.5Y=0.68(X+Y)   0.12X=0.18Y   X=3Y/2   X/(X+Y)=(3Y/2) / (5Y/2)=3/5=40%.   The answer is 40%.
<result>E</result>
Solution X is 80% chemical A and 20% chemical B by volume. Solution Y is 50% chemical A and 50% chemical B by volume. If a mixture of X and Y is 68% chemical A, what percent of the mixture is Solution X?