Problem: the length of the bridge , which a train 130 metres long and travelling at 108 km / hr can cross in 30 seconds , is :
Rationale: "speed = [ 108 x 5 / 18 ] m / sec = 30 m / sec time = 10 sec let the length of bridge be x metres . then , ( 130 + x ) / 30 = 10 = > 130 + x = 300 = > x = 170 m . answer : d"
annotated_formula: subtract(multiply(divide(multiply(108, speed(const_1000, const_1)), speed(const_3600, const_1)), 30), 130)