A canoe is paddled at 2.0 km/h directly across a river that flows at 3.0 km/h, as shown in the figure. What is the resultant speed of the canoe relative to the shore?

Without seeing the figure it's a little tricky, but generally in these problems you can think of the speeds as the edges of a right-angled triangle, and use Pythagoras' theorem to calculate them. So if you paddle across the river at 2km/h and are swept along it at 3km/h, your total speed (going diagonally) will be: