The Purplemath Forums

a chemist needs 10 liters of a 25% acid solution. The solution is to be mixed from three solutions whose concentrations are 10% ,20% ,and 50%. how many liters of each solution should the chemist use to satisfy the following? 1. use as little as possible of the 50% solution. 2. use as much as possibl...

i know how to do the last part but how do i figure out how to do 1 and 2?