Subject: mathqa
Question: two trains of length 100 m and 200 m are 100 m apart . they start moving towards each other on parallel tracks , at speeds 54 kmph and 90 kmph . in how much time will the trains cross each other ?
Option: 
A: 90 / 7 sec
B: 60 / 7 sec
C: 11 sec
D: 10 sec
Answer: D