word problem

Question

A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 60% salt and Solution B is 85% salt. She wants to obtain 130 ounces of a mixture that is 70% salt. How many ounces of each solution should she use?

Answer 1

Let  x = amount of 60% solution, then 130 - x = amount of 85% solution.

 

Salt content of A + Salt content of B = Salt content of mixture

 

0.60x + 0.85(130 - x) = 0.70(130)

0.60x + 110.5 - 0.80x = 91

                           -0.20x = -19.5

                                    x = 97.5

 

Use 97.5 ounces of solution A and 32.5 ounces of solution B to obtain the desired mixture.