A train 75m long takes 6 sec to cross a man walking at 5kmph in a direction opposite to that of the train. Find the speed of the train?  Choose the correct choice from the following options:  A) 35 kmph  B) 40 kmph  C) 45 kmph  D) 50 kmph  E) 55 kmph

Rationale: "let the speed of the train be x kmph speed of the train relative to man = x + 5 = ( x + 5 ) * 5 / 18 m / sec 75 / [ ( x + 5 ) * 5 / 18 ] = 6 30 ( x + 5 ) = 1350 x = 40 kmph answer is b"
Answer: B