doreen needs to prepare 36 oz of a 12% acid solution. what amount of 18% solution and 9% solution should be mixed?

Question

concentration rate. oz of solution oz of pure acid

1st sol. 9%. x. 0.09x

2nd sol. 18%. y. 0.18y

mixture needed 12%. 36. 0.12(36)

Answer 1

x + y = 36

0.09x + 0.18y = 0.12(36)

x = 36 - y

0.09(36 - y) + 0.18y = 4.32

3.24 - 0.09y + 0.18y = 4.32

0.09y = 1.08

y = 12 oz

x = 36 - 12

x = 24 oz