Two trains of length 150 m and 250 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 54 kmph and 36 kmph. In how much time will the trains cross each other?  Choose the correct choice.
A) 87/7 sec  B) 80/7 sec  C) 80/9 sec  D) 80/5 sec  E) 20 sec
Relative speed = (54 + 36)* 5/18 = 5 * 5= 
<gadget id="calculator">5 * 5</gadget>
<output>25</output>
25 mps.   The time required= d/s = (100 + 150 + 250)/25   = 500/25= 
<gadget id="calculator">500/25</gadget>
<output>20</output>
20 sec.   Answer: 20 sec
<result>E</result>
Two trains of length 150 m and 250 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 54 kmph and 36 kmph. In how much time will the trains cross each other?