Question

Some amount of a 120 gram 16% solution was taken out and replaced with pure alcohol. The result was a solution of 30% alcohol. How many grams were taken out?

Answer 1

Answer:

  20 grams

Step-by-step explanation:

Let g represent the grams of solution that were replaced. Then the amount of alcohol in the mix is ...

  16%·(120 -g) +100%·g = 30%·120

  19.2 +0.84g = 36.0 . . . . simplify

  0.84g = 16.8 . . . . . . . . . .subtract 19.2

  g = 20 . . . . . . . . . . . . . . .divide by 0.84

20 grams of solution were taken out and replaced.