a train speeds past a pole in 15 sec and a platform 100 m long in 25 sec , its length is ?
"let the length of the train be x m and its speed be y m / sec . then , x / y = 15 = > y = x / 15 ( x + 100 ) / 25 = x / 15 = > x = 150 m . answer : b"
multiply(100, subtract(const_2, const_1))