# The speed of the boat along the river is 7.2 km / h, and against the current – 4.8 km / h.

The speed of the boat along the river is 7.2 km / h, and against the current – 4.8 km / h. Find the speed of the boat in still water.

To solve this problem, first we need to enter the current velocity for the unknown x, then we know from the condition of the task that the current velocity is the same when the boat is sailing behind the current and against the current:

7.2 – x = 4.8 + x.

7.2 – 4.8 = x + x.

2.4 = 2x

x = 1.2 kilometers per hour – current speed.
Then we can find out what the speed of the boat will be in still water, for this we need the speed of the boat behind the current to subtract the speed of the current, or add the speed of the current to the speed of the boat against the current:

4.8 + 1.2 = 6 kilometers per hour.

Answer: the speed of the boat in still water is 6 kilometers per hour.

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