Answer:
There are 3.2 liters of the 20% solution to be mixed with 4.8 liters of the 70% solution.
Step-by-step explanation:
x = liters of 20% acid solution
y = liters of 70% acid solution
x + y = 8 This represents the total number of liters
and
.2x + .7y = .5(8) This represents the concentration of the solution
Since x+y=8, y = 8-x
We can use substitution.
.2x + .7(8-x) = 4
.2x + 5.6 - .7x = 4
Combining like terms
-0.5x = - 1.6
Dividing by -0.5
x = 3.2
