求助一道数学题

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%

设总人数为X,passengers held round-trip tickets为Y

则x*0.2=(1-0.6)y

y/x=0.2/0.4=50%

不懂对否

agree with fatj