Question

Identify the system of equations used to solve the following problem. A laboratory employee is mixing a 10% saline solution with 4% saline solution. How much of each solution is needed to make 500 milliliters of a 6% solution?

Answer 1

I think with the kinds of mixture problems, it's really helpful to make a table.

The equations you actually need are $x + y = 500$ and $0.1(500-y)+0.04y=30$. Since I was so close, I went ahead and just solved it anyway. You can see my setup on the attached image.