The distance between the two marinas the motor boat runs along the river for 1h. faster than upstream.

The distance between the two marinas the motor boat runs along the river for 1h. faster than upstream. Her own speed is 15 km / h. and the speed of the river is 3 km / h. Find the distance between the marinas.

1. We calculate the speed of the motorboat when moving against the water flow:

15 – 3 = 12 km / h.

2. We calculate the speed of the motorboat when moving in the direction of the flow of water in the river:
15 + 3 = 18 km / h.

3. We take the distance between the piers as x (kilometers).

4. Considering that the motorboat went 1 hour faster down the river than against the current, we make the equation:

x / 12 – x / 18 = 1;

3x – 2x = 36;

x = 36 kilometers.

Answer: the distance between the marinas is 36 kilometers.