Question

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

a) Use the varialbes defined in part a to create a system of linear equations that models the given situation. SHOW YOUR WORK .

b) How many litres of each solution are needed? SHOW YOUR WORK *

c) Verify the solution. SHOW YOUR WORK *​

Answer 1

see below

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 Liters of the 7%

y = 20-7.5

y = 12.5 L of 12%

Check

.07 *7.5 + .15 (12.5) =20*.12

.525+1.875=2.4

2.4=2.4