The boat sailed with the flow for 3 hours. returned 2h. Find your own speed of the boat if the current speed is 4 km / h?

Let the boat’s own speed be x km / h. When the boat is sailing against the current, its own speed decreases by the speed of the river current and is equal to (x – 4) km / h. The boat spends 3 hours on this route, covering a distance of 3 (x – 4) km.

If the boat returns, then it moves with the current at a speed of 4 km / h more than its own and is equal to (x + 4) km / h. The time spent on the same distance is 2 hours, and the return journey is 2 (x + 4) km. Let’s compose and solve the equation:

2 (x + 4) = 3 (x – 4);

2x + 8 = 3x – 12;

2x – 3x = – 12 – 8;

– x = -20;

x = 20;

Answer: the boat’s own speed is 20 km / h.