Question 548187
A container has 6 liters of a 40% solution of alcohol in it. How much pure alcohol should be added to raise it to a 60% solution. 
.
Let x = amount (liters) of pure (100%) alcohol
then
"amt added" + "amt of alcohol at star" = "new percentage"
x + .40(6) = .60(x+6)
x + 2.4 = .60x+3.6
.40x + 2.4 = 3.6
.40x = 1.4
x = 1.4/.40
x = 3.5 liters