the length of the bridge , which a train 500 metres long and travelling at 42 km / hr can cross in 60 seconds , is ?
"speed = [ 42 x 5 / 18 ] m / sec = [ 35 / 3 ] m / sec time = 30 sec let the length of bridge be x metres . then , ( 130 + x ) / 60 35 / 3 = ( 130 + x ) / 60 500 + x = 700 = > x = 200 m answer : b"
subtract(multiply(divide(multiply(42, speed(const_1000, const_1)), speed(const_3600, const_1)), 60), 500)