A motorboat heads upstream on a river that has a current of 3 mph. The trip upstream takes 5 hours and the return trip takes 2.5 hours. What is the speed of the motorboat? (Assume that the motorboat maintains a constant speed relative to the water.)

Distance is not given here.

I assume that r•t = r•t is what we need to set up the equation to find the speed of the motorboat.

Upstream: (r - 3); time = 5 hours

Downstream: (r + 3); time = 2.5 hours

Equation:

(r - 3)5 = (r + 3)(2.5)

Correct?