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 72 kmph. In how much time will the trains cross each other?	Choose the correct choice:
A) 80/9  B) 80/7  C) 80/2  D) 80/1  E) 80/3
Relative speed = (54 + 72)* 5/18 = 7 * 5= 
<gadget id="calculator">7 * 5</gadget>
<output>35</output>
35 mps.   The time required= d/s = (100 + 100 + 200)/35   = 400/35 = 80/7 sec.   Answer: 80/7
<result>B</result>
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 72 kmph. In how much time will the trains cross each other?