The boat covered 64 km along the river in 8 hours, and 12 km upstream in 2 hours. Find the speed of the river.

Initially, we need to find the speed at which the boat went 64 km downstream, and at what speed the boat went 12 km upstream:
64: 8 = 8 km per hour was the speed of the boat downstream;
12: 2 = 6 km per hour was the speed of the boat against the current.
Let’s denote the speed of the current as x, then the speed of the boat on the one hand is equal to (8 – x) km per hour, and on the other – (6 + x) km per hour, respectively, the speed of the boat was the same, then we make the equation:
8 – x = 6 + x;
2x = 2;
x = 1.
Answer: 1 km / h