Question

how many liters of a 10%solution of acid should be added to 20 liters of 60%solution of acid to obtain a 50%solution?

Answer 1

This looks like a chemistry assignment.

Answer 2

Assuming the density doesn't change and the solutions mix with no volume change, the following should do it.
L = liters we need to add.
L(10) + 20(60) = (L+20)*50
Solve for L.

Answer 3

Frank=
You should show the subject matter in the heading. In this case the heading should have been chem or math. Had it not been for Ms Sue, I wouldn't have looked at anything called journal assignment

Answer 4

how many liters of a 10%solution of acid should be added to 20 liters of 60%solution of acid to obtain a 50%solution