Math 113 word problems

Question

How many gallons of a 50% antifreeze solution be mixed with 70 gallons of 15% antifreeze to get a mixture that is 40% antifreeze?

Answer 1

Then, if x is the unknown gallons

{ x(50) + 70(15) }/(x + 70) = 40 or 50x + 1050 = 40x + 2800

10x = 1750 or x =175

Therefore, 175 gallons of the 50% solution is needed for a 40% solution