The motor boat sailed 7 hours along the river and 6 hours against the current. Determine the speed of the river

The motor boat sailed 7 hours along the river and 6 hours against the current. Determine the speed of the river if the speed of the boat in still water is 10 km / h and during the entire trip the boat has covered 132 km.

1. Let’s take the speed of the water flow in the river as x.

2. In the direction of the river flow, the boat sailed for 1 hour (10 + x) kilometers, against the current (10 – x) kilometers.

3. Down the river the boat sailed 7 (10 + x) kilometers, in the opposite direction 6 (10) kilometers.

3. Let’s make the equation:

7 (10 + x) + 6 (10 – x) = 132;

70 + 7x + 60 – 6x = 132;

7x – 6x = 2;

x = 2.

Answer: the speed of water flow in the river is 2 km / h.