How many gallons each of a 45% chlorine solution and a 30% chlorine solution should be mixed to obtained 24 gallons of a 35% chlorine solution?

Answer 1

amount of 45% stuff ---- x gall
amount of 30% stuff ---- 24-x gall

solve for x:
.45 + .3(24-x) = .35(24)
45 + 30(24-x) = 35(24)
...