A scientist has two solutions, which she has labeled Solutuion A and Solution B. Each contains salt. She knows that Solutuion A is 65% salt and Solution B is 90% salt. She wants to obtain 110 ounces of a mixture that is 75% salt. How many ounces of each solution should she use?

a = amount (in oz) of solution A

b = amount of solution B

The scientist wants a mixture of 110 oz, so

a + b = 110

Solution A consists of 65% salt, so each ounce of solution A contributes 0.65 oz of salt; similarly, each ounce of B contributes 0.9 oz. The mixture is supposed to consist of 75% salt, which amounts to 0.75 * (110 oz) = 82.5 oz of salt. So

0.65 a + 0.9 b = 82.5

Solve for a and b:

b = 110 - a

0.65 a + 0.9 (110 - a) = 82.5

0.65 a + 99 - 0.9 a = 82.5

0.25 a = 16.5

a = 66 = => b = 44