math homework

Question

Thirty gallons of a 20% acids solution is needed for an experiment.  Only 40% and 10% acid solutions are available.  How much of each should be mixed to form the needed solution?

Answer 1

Let there be x gallons of 40% solution, mixed with 30-x gallons of 10% solution.

 

The overall effect is x(0.40) + (30-x)(0.10) = x(0.20) ⇐  the acidity equation

 

Solve for x (and then figure 30-x).