Question

A scientist needs 80 liters of a 30​% acid solution. He currently has a 20% solution and a 60% solution. How many liters of each does he need to make the needed 80 liters of 30​% acid​ solution?

Answer 1

If he uses x liters of 20%, then the rest (80-x) must be 60%. Now just look at the amounts of acid present:

.20x + .60(80-x) = .30*80