Question 391607
let x=gallons of 25% solution
500-x = gallons of 50% solution
the total amount of acid in the  two solutions = total acid in the final solution
.25x+.5(500-x) =.34(500)
.25x+250-.5x =170
.25x = 80
x=80/.25 = 320
500-x = 500-320 = 180

ans: 320 gal of 25% solution and 180 gal of 50% solution are required to make 500 gal of 34% solution