Question

How many liters each of a 10% acid solution and a 80% acid solution must be used to produce 70 liters of a 65% acid solution?

Answer 1

Assume you need x liters 10% acid, y liters 80% acid

Then 10%x + 80%y = 65%*70, and x+y = 70

I get: x = 15, y = 55