Question

Grant plans to evaporate enough water from 22 gallons of a 16% ammonia solution to make a 24% ammonia solution. Which equation can he use to find n, the number of gallons of water he should remove?
3.52 (22 minus n) = 0.24
StartFraction 22 minus n Over 3.52 EndFraction = StartFraction 24 Over 100 EndFraction
StartFraction 3.52 Over 22 minus n EndFraction = StartFraction 24 Over 100 EndFraction
3.52 + (22 minus n) = 0.24

Answer 1

Use the fact the amount of ammonia stays 3.52 gallons (0.16·22). The concentration equation is
3.52 / (22 − n) = 0.24.

(If you solve it: 3.52 = 0.24(22 − n) → n = 7.333... gallons ≈ 7 1/3.)