Answer
We need to mix 30 liters of the 10% salt solution.
Work Step by Step
Let X represent the amount of the 10% salt solution that is to be mixed.
The second solution is 15 liters.
That means that the final solution will be 15 + X = 15 + X liters.
We use the following guideline to solve this problem:
Amount of salt in the first solution + Amount of salt in the second solution = Amount of salt in final solution.
10% $\times$ X +40% $\times$ 15= 20% $\times$ (15 + X)
$ .1 \times X + .4\times 15 = .2 \times (15+X)$
0.1X + 6 = 3 + 0.2X
3 = 0.1X
Divide both sides by 0.1
30 = X
We need to mix 30 liters of the 10% salt solution.
