How much of each solution should she use?

Question

Kelly, a chemist, was asked to prepare 24 gallons of a solution that is 50% acidic by mixing a solution that is 20% acidic with another solution that is 70% acidic. How much of each solution should she use? 

Answer 1

x represents amount of 20% solution

24 - x represents amount of 70% solution

0.20x + 0.70(24 - x) = 0.50(24)

2x + 7(24 - x) = 5(24) 2x + 186 - 7x = 120 -5x + 186 = 120 -5x = -48 x = 9.6