If 20 liters of chemical X are added to 80 liters of a mixture that is 20% chemical X and 80% chemical Y, then what percentage of the resulting mixture is chemical X? Select the correct option.
A) 30% B) 33% C) 36% D) 39% E) 42%
The amount of chemical X in the solution is 20 +0.2(80) = 36 liters.   36 liters / 100 liters = 36%   The answer is 36%.
<result>C</result>
If 20 liters of chemical X are added to 80 liters of a mixture that is 20% chemical X and 80% chemical Y, then what percentage of the resulting mixture is chemical X?