！問一個白痴問題！拜託，麻煩了！ 
Q18.
On a certain transaltantic crossing, 20% of a ship's passengers held round-trip tickets and also took their cars abroad the ship. If 60% of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship's passengers held round-trip tickets?
A. 33 1/3%
B. 40%
C. 50%
D. 60%
E. 66 2/3%
