GWD 31-2-18,没有思路

Q18:

On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship.  If 60 percent 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%

答案C

对于这种题目，没有思路？谁能帮忙翻译并解释一下？tks

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=119537&replyID=&skin=1

以后做GWD题有疑问时，可先用搜索功能，很多题目前人已提过并有解决方法；如果真的搜索不到，再发贴上来问la。

方法：如果GWD第3套Q5，则搜索的关键词：3-5

抱歉刚才没找到，谢谢斑竹。