Alegebra application

Question

How many quarts of pure antifreeze must be added to 2 quarts of a 20% antifreeze solution to obyain 60% antifreeze solution?

Answer 1

2 quarts. 60 is halfway between 20 and 100, so you need equal amounts. 2 quarts of 20 means you need 2 quarts of 100

100P + 20T = 60(2+P)

100P +20(2) = 60(2+P)

100P + 40 = 120 + 60P

100P-60P = 120-40

40P= 80

P = 80/40 = 2 quarts of pure antifreeze