# It took 3 hours to row a boat 18 km against the current. The return trip with the current took 1 1/2 hours. How do you find the speed of the rowboat in still water?

##### 1 Answer

Oct 28, 2015

The speed is 9 km/h.

#### Explanation:

Boat speed = Vb

River speed = Vr

If it took 3 hours to cover 18km, the average speed

For the return trip, the average speed is

According to the second equation,

Substituting in the first equation: