The boat went 84 km / h, 5 hours upstream and 3 hours downstream.

The boat went 84 km / h, 5 hours upstream and 3 hours downstream. In this case, the speed of the current is 2 km / h. Make an equation and find the boat’s own speed.

Let’s designate the boat’s own speed as x km / h, then the speed with which it sailed along the river will be equal to (x + 2) km / h, and against the current (x – 2) km / h. It is known that he covered 84 km. Let’s compose and solve the equation:

(x + 2) * 3 + (x – 2) * 5 = 84;

6 + 3x + 5x – 10 = 84;

8x = 88;

x = 88: 8;

x = 11 (km / h).

Answer: the boat’s own speed is 11 km / h.