The boat sailed along the river for 24 km and came back, spending 5 hours for the whole journey

The boat sailed along the river for 24 km and came back, spending 5 hours for the whole journey. Find your own boat speed if the river speed is 2 km / h.

Let’s define that the boat’s own speed is x km / h. Let us write down the speed of the boat moving with the current and against the current, if it is known that the speed of the current is 2 km / h.
(x + 2) km / h – downstream;
(x – 2) km / h – against the current.
According to the condition, it was said that the whole journey took 5 hours. Let’s compose and solve the equation:
24 / (x + 2) + 24 / (x – 2) = 5
24x – 48 + 24x + 48 = 5x² – 20
5x² – 48x – 20 = 0
D = 2704, x1 = 10, x2 = -0.4.
Only x = 10 suits us – this is the boat’s own speed.
Answer: 10 km / h.