5.7 liters of 5% solution and 4.3 liters of 40% solution.
First, create some formulas to define the problem.
x Amount of 5% solution used
10-x Amount of 40% solution used
This equation means 5% of x plus 40% of (10-x) equals 20% of 10.
0.05x + 0.40(10-x) = 0.20 * 10
Distribute the 0.40
0.05x + 4.0 - 0.40x = 0.20 * 10
Combine terms
4.0 - 0.35x = 2.0
Add 0.35x to both sides
4.0 = 2.0 + 0.35x
Subtract 2 from both sides
2.0 = 0.35x
Divide both sides by 0.35
5.7 = x
So we need to use 5.7 liters of the 5% solution. To get the amount of 40% solution, just simply subtract from 10.
10.0 - 5.7 = 4.3
