Question 819030
A chemist has 100 liters of 20% sodium chloride solution. She intends to drain a certain number of liters and replace with a more concentrated solution.
a) How much of this solution should she drain and replace with 70% sodium chloride if she wants a 35% sodium chloride solution?
.2*100-.2x+.7x=.35*100
20+.5x=35
.5x=15
x=30
check

70*.20+.70*30=.35(100)
14+21-35
35=35
ok