Answer:
15 liters
Step-by-step explanation:
Let v represent the number of liters of 10% solution to be mixed with 5 liters of a 50% solution to obtain a 20% solution. The amount of salt in the final solution is ...
0.10x +0.50(5) = 0.20(x+5)
1.5 = 0.10x . . . . . simplify, subtract 1+0.10x
15 = x . . . . . . . . . multiply by 10
15 liters of 10% solution must be added.
