a train 225 m long passes a man , running at 10 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 = 225 / 10 m / sec = 45 / 2 m / sec . = 45 / 2 x 18 / 5 km / hr = 81 km / hr . let the speed of the train be x km / hr . then , relative speed = ( x - 5 ) km / hr . x - 10 = 81 = 91 km / hr . answer : c"
divide(divide(subtract(225, multiply(multiply(10, const_0_2778), 10)), 10), const_0_2778)