the length of the bridge , which a train 150 m long and traveling at 45 km / hr can cross in 30 sec is ?
"speed = 45 * 5 / 18 = 25 / 2 m / sec . time = 30 sec let the length of bridge be x meters . then , ( 150 + x ) / 30 = 25 / 2 x = 225 m . answer : b"
subtract(multiply(divide(multiply(45, speed(const_1000, const_1)), speed(const_3600, const_1)), 30), 150)