Question 499482
how many gallons of 50% antifreeze solution must be mixed with 80 gallons of 15% anifreeze to get a mixture that is 40% anitfreeze? 
.
Let x = amount (gallons) of 50% antifreeze
then
.50x + .15(80) = .40(x + 80)
.50x + 12 = .40x + 32
.10x + 12 = 32
.10x = 20
x = 200 gallons