The speed of the motor boat along the river is 27 km / h, and against the current 19 km / h.

The speed of the motor boat along the river is 27 km / h, and against the current 19 km / h. Find the speed of the motorboat on the lake.

The speed of a motor boat on the lake is equal to the boat’s own speed.

Let the boat’s own speed be x km / h.

To find the speed along the river, you need to add the speed of the current to the boat’s own speed, which means the speed of the current is:

(27 – x) km / h.

To find the speed against the flow of the river, it is required to subtract the speed of the current from the boat’s own speed, which means that the speed of the current is:

(x – 19) km / h.

Let’s compose and solve the equation:

27 – x = x – 19,

2x = 46,

x = 23 km / h.

Answer: the speed of the boat on the lake is 23 km / h.