In a certain parking lot, 10% of the cars are towed for parking illegally. However 80% of the cars which are parked illegally are not towed. What percentage of cars in the parking lot are parked illegally?	Choose the most appropriate option.
A) 30%
B) 40%
C) 50%
D) 60%
E) 70%
Let x be the number of cars and let y be the number of cars parked illegally.   10%*x = 20%*y   y/x = 1/2 = 50%   The answer is 50%.
<result>C</result>
In a certain parking lot, 10% of the cars are towed for parking illegally. However 80% of the cars which are parked illegally are not towed. What percentage of cars in the parking lot are parked illegally?