Answer:
8 cups of shampoo concentrate
Step-by-step explanation:
let x=how much shampoo concentrate Devin should add
[tex]\frac{2}{9} =\frac{x}{36}[/tex]
cross multiply
2*36=9x
72=9x
72/9=x
x=8
Devin should add 8 cups of shampoo concentrate to the water to make the shampoo solution.