How many liters of water must be evaporated from 50 liters of a 4-percent sugar solution to get a 10-percent solution?  Select:
A) 30
B) 32
C) 34
D) 36
E) 38
4% of a 50 liter solution is 2L which is 10% of the solution at the end.   The solution at the end must be 20 L.   We need to evaporate 30 liters.   The answer is 30.
<result>A</result>
How many liters of water must be evaporated from 50 liters of a 4-percent sugar solution to get a 10-percent solution?