Paint costs $21 per gallon is to be mixed with 6 gallons of paint thinner costing $5 per gallon to make a paint that can be $15 per gallon. Compute how much paint mixture will be produced.

Answer 1

Let the quantity of paint be x gallons, then
cost of paint = $21x
cost of thinner = 6*$5

cost of mixture = $15*(x+6)
therefore
21x+6*5 = 15(x+6)

Solve for x.

Answer 2

10