A crew team rows a boat at a rate of 20 km/h in still water. In practice on a river, the team rows for 30 minutes up the river, and then for 30 minutes down the river. The speed of the river current is 1.5 km/h. How long did it take for them to return to the starting point?
A crew team rows a boat at a rate of 20 km/h in still water. In practice on a river, the team rows for 30 minutes up the river and then for 30 minutes down the river. The speed of the river current is 1.5 km/h. How much farther did they travel in the 2nd 30 minutes?