How much time will a train of length 300 m moving at a speed of 72 kmph take to cross another train of length 500 m, moving at 36 kmph in the same direction?  Choose the correct choice from the following answers:
A) 50
B) 80
C) 88
D) 76
E) 12

Rationale: "the distance to be covered = sum of their lengths = 300 + 500 = 800 m . relative speed = 72 - 36 = 36 kmph = 36 * 5 / 18 = 10 mps . time required = d / s = 800 / 10 = 80 sec . answer : b"
Answer: B