How many gallons of 20% alcohol solution should be added to 40 gallons of a 50% alcohol solution to make a 30% solution?
+37157 alcohol in ingredients = alcohol in final soln
x = 20% volume
40 = 50% volume
(x+40) = 30% volume
.20(x) + .50(40) = .30(x+40)
.2x + 20 = .3x + 12
.1x = 8
x = 80 gallons of 20% alcohol needed
