Algebra homework

Question

Alcohol mixture: in a chemistry class, 12 liters of a 12% alcohol solution must be mixed with a 205 solution to get a 14% solution. How many liters of the 20% solution are needed??

Answer 1

20-14 = 6, 14-12 =2 6/2 = 3 times as much 12% as 20%

12L = 3 times 4 Liters of 20%

or the more conventional method

.12(12+ .2x = .14(x+12)

1.44 + .2x = .14x + 1.68

.06x = .24

x = .24/.06 = 24/6 = 4 Liters of 20%