Question

An automobile's radiator has a capacity of fifteen quarts, and it currently contains twelve quarts of a thirty percent antifreeze solution. How many quarts of pure antifreeze must be added to strengthen the solution to forty percent?
2 quarts
3 quarts
4 quarts

Answer 1

12 + x = y
12(.30) + 1x = y(.40)

Answer 2

The 15 is a trick

Answer 3

12 + x = y
3.6 + x = .4y

.4(12 + x) = 3.6 + x
4.8 + .4x = 3.6 + x
4.8 - 3.6 = x - .4x
1.2 = .6x
1.2/.6 = x
2 = x

Answer 4

Therefore, 2 quarts must be added to get the 40%

Answer 5

thank u