a train 100 m long crosses a platform 250 m long in 7 sec ; find the speed of the train ?
"d = 100 + 250 = 350 t = 7 s = 350 / 7 * 18 / 5 = 180 kmph answer : d"
subtract(multiply(7, multiply(const_60.0, const_0_2778)), 100)