Question

A 7% acid solution will be mixed with a 15% acid solution. 20 L of a 12% acid solution needs to be made.

Identify the two variables in the problem by completing the following statements: * Let r represent: Let y represent:​

Answer 1

Let r = amount of the 7% solution

y represent the amount of the 15 percent solution

r =7.5 L

y = 12.5 L

Explanation:

Let r = amount of the 7% solution

y represent the amount of the 15 percent solution

.07r + .15 y = (r+y) .12

r+y = 20

y = 20-r

.07r + .15 (20-r) = (20) .12

0.07r+0.15(20-r)=2.4

.07r+ 3 - .15r = 2.4

-.08r = 2.4-3

-.08r = -.6

Divide by-.08

r =7.5

y = 20-7.5

y = 12.5