The hydrofoil sailed 84 km against the river. How long was the boat on the way, if the boat’s own speed

The hydrofoil sailed 84 km against the river. How long was the boat on the way, if the boat’s own speed was 30 km / h and the river speed was 2 km / h.

The boat was sailing against the stream of the river, so to calculate its speed, you need to subtract the speed of the river from its own speed:

30 – 2 = 28 (km / h).

Now, to calculate the travel time, you need to divide the distance traveled by the speed of the boat:

84/28 = 3 (h).

Answer: the boat was on the way for 3 hours.