Subject: mathqa
Question: two trains of equal length , running with the speeds of 60 and 40 kmph , take 75 seconds to cross each other while they are running in the same direction . what time will they take to cross each other if they are running in opposite directions ?
Option: 
A: 67 sec
B: 13 sec
C: 16 sec
D: 15 sec
Answer: D