Tricks: Time taken for walking one way = Time taken walking both ways/2 = (55/2) = 27.5 mins. Time for riding one way= 37 - 27.5 = 9.5 mins. Time taken to ride both way = 9.5 × 2 = 19 mins Detailed solution: Let the speed at walking and riding be ‘x’ and ‘y’ km/hours respectively and the distance be ‘d’ km in one direction Total time = Time for walking + Time for riding ∴ 37/60 = d/x + d/y ----(1) For walking both ways, 55/60 = d/x + d/x ∴ d/x = 55/120 Substituting in (1) we get, 55/120 + d/y = 37/60 ∴ d/y = 19/120 ----(2) For riding both ways, Time = d/y + d/y = 2(d/y) = 2 × (19/120) = 19 min ∴ To ride both ways, the person will take 19 min