How much time will a train of length 420 m moving at a speed of 72 kmph take to cross another train of length 640 m, moving at 36 kmph in the same direction?  Choose the correct choice
A) 50 B) 99 C) 88 D) 76 E) 106
The distance to be covered = Sum of their lengths = 420 + 640= 
<gadget id="calculator">420 + 640</gadget>
<output>1_060</output>
1060 m.   Relative speed= 72 -36= 
<gadget id="calculator">72 -36</gadget>
<output>36</output>
36 kmph= 36 * 5/18= 
<gadget id="calculator">36 * 5/18</gadget>
<output>10</output>
10 mps.   Time required= d/s = 1060/10= 
<gadget id="calculator">1060/10</gadget>
<output>106</output>
106 sec.   Answer:106
<result>E</result>
How much time will a train of length 420 m moving at a speed of 72 kmph take to cross another train of length 640 m, moving at 36 kmph in the same direction?