SOLUTION: How much pure antifreeze should be added to a gallon of 70% antifreeze solution to make a 90% antifreeze solution?

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Question 227659: How much pure antifreeze should be added to a gallon of 70% antifreeze solution to make a 90% antifreeze solution?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
How much pure antifreeze should be added to a gallon of 70% antifreeze solution to make a 90% antifreeze solution?
.
Let x = amount of pure antifreeze added
then
x + .70(1) = .90(x+1)
x + .70 = .90x+.90
.10x + .70 = .90
.10x = .20
x = .20/.10
x = 2 gallons