System of Equations Word Problems

Question

A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 65% salt and Solution B is 85% salt. She wants to obtain 120 ounces of a mixture that is 80% salt. How many ounces of each solution should she use?

Answer 1

A=amt of A and B=amt of B

A+B=120

.65A+.85B=.8*120

You can do this one of 2 ways:

Multiply 1st equation by 65 and 2nd equation by 100, then subtract to eliminate A or

Set A=120-B and substitute into the 2nd equation.

Either way the arithmetic is about equally messy.