Question 281845
One solution is 80% acid and another one is 30% acid. How much of each solution is needed to make a 200L solution that is 62% acid? 
.
Let x = amount of 80% acid
then
200-x = amount of 30% acid
.
Our equation:
.80x + .30(200-x) = .62(200)
.80x + 60 - .30x = 124
.50x + 60 = 124
.50x = 64
x = 128 L (80% acid)
.
30% acid:
200-x = 200-128 = 72 L (30% acid)