The boat sailed along the river for 5 hours, and against the river for 3 hours. The boat’s own speed is 18 km / h.

The boat sailed along the river for 5 hours, and against the river for 3 hours. The boat’s own speed is 18 km / h. find the speed of the river if the boat sailed 48 km downstream. more than upstream

Let the speed of the river flow be x km / h, then the speed of the boat along the river is (18 + x) km / h, and the speed of the boat against the river is (18 – x) km / h. The boat traveled along the river in 5 hours a distance of 5 (18 + x) kilometers, and in 3 hours against the river – 3 (18 – x) kilometers. According to the condition of the problem, it is known that the path of the boat along the course of the river is greater than the path of the boat against the course of the river by (5 (18 + x) – 3 (18 – x)) kilometers or 48 kilometers. Let’s make an equation and solve it.

5 (18 + x) – 3 (18 – x) = 48;

90 + 5x – 54 + 3x = 48;

8x + 36 = 48;

8x = 48 – 36;

8x = 12;

x = 12: 8;

x = 1.5 (km / h).

Answer. 1.5 km / h.