Two trains of length 100 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 36 kmph and 72 kmph. After how much time will the trains meet?  Choose the correct answer:
A) 10/3 sec	B) 20/7 sec	C) 33/7 sec	D) 21/7 sec	E) 32/7 sec
They are moving in opposite directions, relative speed is equal to the sum of their speeds.   Relative speed = (36 + 72)*5/18 = 6*5= 
<gadget id="calculator">6*5</gadget>
<output>30</output>
30 mps.   The time required= d/s = 100/30 = 10/3 sec.   10/3 secnswer : 10/3 sec
<result>A</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 36 kmph and 72 kmph. After how much time will the trains meet?