Question

Faith mixes 14 liters of 12% acid solution with a 30% acid solution which results in an 18% acid solution.

Find the number of liters of 30% solution in the new mixture.

Answer 1

x = amount of second solution
y = total amount of mixed solution

14 + x = y
14(.12) + x(.30) = y(.18)

Answer 2

Solve the system

Answer 3

.30x - 0.18y = -1.68
x - y = -14
-0.18x + 0.18y = 2.52
add 1st and 3rd eqns

0.12x = 2.52-1.68 = 0.84
x = 7
14+7 = y = 21

check
21 (.18) = 3.78

14(.12) + 7(.30) = 3.78 right