Subject: mathqa
Question: on a certain transatlantic crossing , 40 percent of a ship ’ s passengers held round - trip tickets and also took their cars abroad the ship . if 20 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 ?
Option: 
A: 80 %
B: 40 %
C: 50 %
D: 60 %
Answer: C