a train 105 m long passes a man , running at 5 km / hr in the same direction in which the train is going , in 10 seconds . the speed of the train is :
speed of the train relative to man = ( 105 / 10 ) m / sec = ( 21 / 2 ) m / sec . [ ( 21 / 2 ) * ( 18 / 5 ) ] km / hr = 37.8 km / hr . let the speed of the train be x km / hr . then , relative speed = ( x - 5 ) km / hr . x - 5 = 37.8 = = > x = 42.8 km / hr . answer : c
divide(divide(subtract(105, multiply(multiply(5, const_0_2778), 5)), 10), const_0_2778)