Problem: a boatman selling a boat along river flow . if he sell boat in steal water at 3 m / sec and flow of river is 2 m / sec . how much time he will take to sell 100 m .
Rationale: net speed = 3 + 2 = 5 m / sec distance = 100 m time = 100 / 5 = 20 sec answer d
annotated_formula: divide(100, add(3, 2))