Systems of Linear Equations

Question

A chemist has three different acid solutions. The first acid solution contains  acid, the second contains  and the third contains . They want to use all three solutions to obtain a mixture of  liters containing  acid, using  times as much of the  solution as the  solution. How many liters of each solution should be used?

Answer 1

Lets say amount of 55% is x;

amount of 25% is 2x;

amount of 15% is 96 - 3x (because total is 96)

the equation is (96-3x)*15+55x+25*2x=96*30

solve this equation for x