Question 27688
Let speed in still water = x km/hr
Let speed of river = y km/hr

speed with river is x+y
speed against river is x-y


with river:
x+y = 50/5
x+y = 10


against river:
x-y = 25/5
x-y = 5


so, add the 2 equations together: 2x = 15 --> x = 7.5 km/hr
and therefore from x+y=10, y = 2.5 km/hr


jon.