Problem: a boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 15 minutes . how long will it take to go 5 km in stationary water ?
Rationale: "speed ( upstream ) = 2 / 1 = 2 kmhr speed ( downstream ) = 1 / ( 15 / 60 ) = 4 kmhr speed in still water = 1 / 2 ( 2 + 4 ) = 3 kmhr time taken in stationary = 5 / 3 = 1 hrs 40 min answer : e"
annotated_formula: divide(5, divide(add(multiply(divide(1, 15), const_60), divide(2, 2)), const_2))