求解高人！！

Jolie881209

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%
Answer: c

VenciTan

20 percent of a ship’s passengers held round-trip tickets(设为B) and also took their cars abroad the ship
说的是总人口（设为A）里有20%的人held round-trip tickets and also took their cars abroad the ship,都有的设为C， C/A=20%；
If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship
说的是所有with round-trip tickets的人当中(B），60%没有CAR...，也就是说40%有，C/B=40%。。。
综上B/A=50%

主要是理解If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship这句话