Question

Лодка плыла 4 ч по реке против течения. За это время она проплыла 30 км. Скорость течения реки 3 км/ч. Найдите собственную скорость лодки. Составьте уравнение по условию задачи.

Answer 1

 х км/ч - собственная скорость.
4(х-3)=30

Answer 2

Let's assume the speed of the boat is v km/h.

When the boat is moving against the current, its effective speed is reduced by the speed of the current. Therefore, the speed of the boat against the current is v - 3 km/h.

The boat traveled for 4 hours, so the distance it covered is the product of its speed and the time: (v - 3) * 4 = 30 km.

Now we can form an equation based on the given condition:

4(v - 3) = 30

Let's solve this equation to find the value of v.

4v - 12 = 30

4v = 42

v = 10.5

Therefore, the speed of the boat in still water is 10.5 km/h.