A lab assistant wants to make 5 liters of 27.2% acid solution. If solutions of 30% and 16% are in stock, how many liters of each must be mixed to prepare the solution?

Let x = 30% y=16%

We need 5 liters of 27.2% acid

A) x + y = 5

B).30 x +.16y = 5 *.272

Multiplying A by -.30

A) -.30 x -.30y = - 1.5 then adding to B

B).30 x +.16y = 1.36

-.14y = -.14

y = 1 liter 16%

x = 4 liters 30%