The boat covered the distance behind the current in 2 hours, and against the current in 2.5.

The boat covered the distance behind the current in 2 hours, and against the current in 2.5. The speed of the current is 2 km / h. Find the distance between the pier.

Let’s assume that the boat’s own speed is x km / h.

Since the speed of the current is 2 km / h, the boat will go downstream at a speed of x + 2 km / h, and against the current at a speed of x – 2 km / h.

According to the condition of the problem, we compose and solve the following equation:

2 * (x + 2) = 2.5 * (x – 2),

2 * x + 4 = 2.5 * x – 5,

2.5 * x – 2 * x = 4 + 5,

0.5 * x = 9,

x = 9: 0.5,

x = 18 (km / h) – own speed of the boat.

Answer: 18 km / h.