Doc has available to have a 20% alcohol solution and a 70% alcohol solution how many liters of each solution should be mixed to make 30 L of a 50% alcohol solution?
We have this equation
.20 x + .70 ( 30 - x) = .50 (30) simplify
.20 x + 21 - .70x = 15
-.50x + 21 = 15 subtract 21 from both sides
-.5x = -6 divide both sides by - .5
x = 12 [ L of 20% solution ]
(30 - x) = (30 -12) = 18 [ L of 70% solution ]
