The boat goes 80 km along the lake in 2 hours. What distance will he cover in the same time along the river, the speed

The boat goes 80 km along the lake in 2 hours. What distance will he cover in the same time along the river, the speed of which is 1 km / h, if the boat moves: 1) along the river 2) against the river.

1. Determine the speed of the boat in still water:
80: 2 = 40 km / h;
2. Determine the speed of the boat downstream: 40 + 1 = 41 km / h;
3. Determine the distance that the boat will sail downstream in 2 hours:
41 x 2 = 82 km;
4. Determine the speed of the boat against the current:
40 – 1 = 39 km / h;
5. Determine the distance that the boat will sail against the current in 2 hours:
39 x 2 = 78 km.
Answer: the boat will sail downstream for 82 kilometers in 2 hours; The boat will sail 78 kilometers against the current in 2 hours.