Problem: two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 1.10 km and 1.9 km respectively . the time taken by the slower train to cross the faster train in seconds is ?
Rationale: "relative speed = 60 + 90 = 150 km / hr . = 150 * 5 / 18 = 125 / 3 m / sec . distance covered = 1.10 + 1.9 = 3 km = 3000 m . required time = 3000 * 3 / 125 = 72 sec . answer : b"
annotated_formula: subtract(divide(multiply(1.10, const_1000), divide(multiply(60, const_1000), const_3600)), divide(multiply(1.9, const_1000), divide(multiply(90, const_1000), const_3600)))