Two trains of length 100 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 72 kmph and 90 kmph. In how much time will the trains cross each other? Select
A) 80/8	B) 80/9	C) 80/5	D) 80/3	E) 80/1
Relative speed = (72 + 90)* 5/18 = 9* 5= 
<gadget id="calculator">9* 5</gadget>
<output>45</output>
45 mps.   The time required= d/s = (100 + 100 + 200)/45   = 400/45 = 80/9 sec.   Answer: 80/9
<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 72 kmph and 90 kmph. In how much time will the trains cross each other?