a train speeds past a pole in 25 seconds and a platform 150 m long in 30 seconds . its length is ?
"let the length of the train be x meters and its speed be y m / sec . they , x / y = 25 = > y = x / 25 ( x + 150 ) / 30 = x / 25 x = 30 m . answer : d"
multiply(150, subtract(const_2, const_1))