The boat sails the distance between two villages on the banks of the river, 3 hours against the river

The boat sails the distance between two villages on the banks of the river, 3 hours against the river and 2 hours 20 minutes along the river. The speed of the river is 3 km / h. What is the boat’s own speed?

To solve the problem, we will designate the boat’s own speed as “a” km / h.

Then, the speed with which the boat sailed with the current and against the current will be equal to “a + 3” and “a – 3” km / h.

Let’s compose an equation, taking into account that the distance between the villages against the current the boat sails in 3 hours, and downstream in 2 hours 20 minutes (2 1/3 hours):

3 * (a – 3) = 2 1/3 * (a + 3);

3a – 9 = 2 1 / 3a + 21/3;

7 + 9 = 3a – 2 1 / 3a;

16 = 2 / 3a;

a = 16 / 2/3;

a = 16 * 3/2;

a = 24 km / h.

Answer: the boat has a speed of 24 km / h.