Calculating % of salt in a solution

Question

A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 40% salt and Solution B is 90% salt. She wants to obtain 80 ounces of a mixture that is 60% salt. How many ounces of each solution should she use?

Answer 1

s represents the amount of 40%

80 - s represents the amount of 90%

0.40s + 0.90(80 - s) = 0.60(80)

 

Can you solve for s and answer?