Using the relation between velocity, distance and time, it is found that the speed of the boat is of 15 km/h.
Velocity is distance divided by time, that is:
[tex]v = \frac{d}{t}[/tex]
Going downstream, the boat has the current in it's favor, hence:
[tex]v_b + v_c = \frac{d}{2}[/tex]
[tex]v_b + 3 = \frac{d}{2}[/tex]
[tex]d = 2v_b + 6[/tex]
Going upstream, the boat goes against the current, hence:
[tex]v_b - v_c = \frac{d}{3}[/tex]
[tex]v_b - 3 = \frac{d}{3}[/tex]
[tex]d = 3v_b - 9[/tex]
The distances are equal, hence:
[tex]3v_b - 9 = 2v_b + 6[/tex]
[tex]v_b = 15[/tex]
The speed of the boat is of 15 km/h
More can be learned about the relation between velocity, distance and time at https://brainly.com/question/24316569
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