A watercraft is rowed down 32 km along a river in 4 hours and 10 km against the river in 5 hours. Find the speed of the watercraft and that of the river.

5 km/h and 3 km/h

We know that,

Upstream Speed = Speed of Boat – Speed of current

Downstream Speed = Speed of Boat + Speed of current

Distance = Speed × time

Let the speed of watercraft be x and river be y

Time taken by watercraft while moving down for 32 km is 4 hours

In one hour = 8 km/h =  x + y ----(1)

Time taken by watercraft while moving against for 10 km is 5 hours,

In one hour = 2 km/h = x + y ----(2)

On solving the equation (1) and (2)

x = 5 km/h and y = 3 km/h