Mixture problem?

Question

A chemist has a solution that is 60% saline and another solution that is 35% saline. How many ounces of each solution will she need to make 100 ounces of a mixture that is 40% saline?

Please help.

Answer 1

.6v + .35(100-v) = .4*100
or .25v = 5
or v = 20

20 ounces of 60 % and 80 ounces of 35 %