Question

a science teacher has supply of 20% saline solution and a supply of 50% saline solution. How much of each solution should the teacher mix together to get 60 ml of 28% saline solution for an experiment?

Answer 1

0.2*(v1)+0.5*(v2) = (.28)(60)

(v1)+(v2) = 60

Answer 2

The first equation equates the amount of solute.
The second equates total volume.