Doreen Schmidt is a chemist. She needs to prepare 24 ounces of a ​7% hydrochloric acid solution. Find the amount of 12​% solution and the amount of 6​% solution she should mix to get this solution.

Question

help plz

Answer 1

12-7 = 5

7-6 = 1

5 times as much of 6% is needed as 12%

5 x 4 = 20, 20 of 6%, 4 of 12%

divide 24 by 6 = 4

4 ounces of 12% mixed with 20 ounces of 6% yield 24 ounces of 7%

.12(4) + .06(20) = .48+ 1.2 = 1.68

.07(24) = 1.68

or another more popular approach

.12x + .06(24-x) = .07(24)

.12-.06x = .07(24) -.06(24)

.06x = .01(24) = .24

x =.24/.06 = 4 ounces of 12%

24-x = 24-4 = 20 ounces of 6%