Question 1009305
Let x be the amount of 50% solutioin.
Thus 50-x will be the amount of 40% solution.
The set up is then
.50x + .40(50-x) = .47(50)
.50x + 20 - .40x = 23.5
.10x = 3.5
x = 35 gallons of 50% solution
50-x = 15 gallons of 40% solution