Problem: a train which has 420 m long , is running 45 kmph . in what time will it cross a person moving at 9 kmph in same direction ?
Rationale: "time taken to cross a moving person = length of train / relative speed time taken = 420 / ( ( 45 - 9 ) ( 5 / 18 ) = 420 / 36 * ( 5 / 18 ) = 420 / 10 = 42 sec answer : b"
annotated_formula: divide(420, subtract(divide(45, const_3_6), divide(divide(9, const_2), const_3_6)))