A train leaves Mumabai at 9 am at a speed of 40 kmph. After one hour, another train leaves Mumbai in the same direction as that of the first train at a speed of 80 kmph. When and at what distance from Mumbai do the two trains meet?  Answers:  A) 87  B) 279  C) 80  D) 278  E) 379

Rationale: "when the second train leaves mumbai the first train covers 40 * 1 = 40 km so , the distance between first train and second train is 40 km at 10.00 am time taken by the trains to meet = distance / relative speed = 40 / ( 80 - 40 ) = 1 hours so , the two trains meet at 11 a . m . the two trains meet 1 * 80 = 80 km away from mumbai . answer : c"
Answer: C