Question

A scientist needs 80 liters of a 30% solution of alcohol. She has a 20% solution and a 60% solution available. How many liters of the 20% solution and how many liters of the 60% solution should she mix to make the 30% solution?

Answer 1

80 times .30= .20x +.60(80-x)
24=.20x+48-.60x
Subtract 48 from both sides
-24=-.40x
Divide both sides by-.40
X= 60
60 liters of 20%