The river speed is related to the boat’s own speed as 2: 5. Find the river speed and the boat’s own speed if it is known

The river speed is related to the boat’s own speed as 2: 5. Find the river speed and the boat’s own speed if it is known that in 4 hours the boat has climbed 18 km up the river.

Let the speed of the river flow – x, then the boat’s own speed:

5x / 2 = 2.5x.

We know that the boat against the stream of the river covered 18 km in 4 hours, that is, at a speed:

18: 4 = 4.5 (km / h) – boat speed against the river flow.

We express the speed of the boat against the river flow in x and find the speed of the river flow:

2.5 – x = 4.5,

1.5x = 4.5,

x = 4.5 / 1.5 = 3 (km / h) – river flow speed.

3 * 2.5 = 7.5 (km / h) – the boat’s own speed.

Answer: 3 km / h, 7.5 km / h