Question 233645
    How much 30% solution and 70% solution need to be combined to make 80 ml of a 60% solution?
.
Let x= amount of 50% solution added
then
80-x = amount of 70% solution added
.
.30x + .70(80-x) = .60(80)
.30x + 56 - .70x = 48
56 - .40x = 48
-.40x = -8
x = 32 ml (of 30% solution)
.
70% solution:
80-x = 80-32 = 48 ml (of 70% solution)