A boat covers a distance of 12 km in 1 hour upstream and in 45 minutes downstream. Find the speed of the boat and the stream (in km/h).

​Given:

Distance covered = 12 km (both upstream and downstream)

Time taken upstream = 1 hour

Time taken downstream = 45 minutes = 45/60 = 0.75 hours

Upstream speed, U = u – v km/h

(When the boat is moving against the current, the effective speed is reduced by the speed of the stream.)

Downstream speed, D = u + v km/h

(When the boat is moving with the current, the effective speed is increased by the speed of the stream.)

Where, u is speed of boat, v is speed of stream.

​$$\text{Speed} = \frac{\text{Distance}}{\text{Time}}$$​​

​