arithmetic - a man can row 75 kmhr in still water if in a river running at 15 kmhr it takes him 50 minutes to row to a place and back how far off is the place - skillgun

Let the required distance be x km.
Speed upstream = (7.5 - 1.5) = 6 km/hr,
Speed downstream = (7.5 + 1.5) = 9 km/hr.
Total time = time taken to cover distance in both upstream and downstream
=> 50/60 = x/6 + x/9
=> (15x)*6 = 54*5 = > x = 3 km.