Subject: mathqa
Question: two trains leave the train station at the same time . one train , on the blue line , heads east - while the other , on the red line , heads west . if the train on the blue line averages 40 km / hr and the other train averages 40 km / hr - how long will it take for the trains to be 100 km apart ?
Option: 
A: 1 hour
B: 1.25 hours
C: 2 hours
D: 2.25 hours
Answer: B