can you help me through this?

Question

A boat moves through a river at 7.0 m/s relative to the water, regardless of the boat's direction. If the water in the river is flowing at 3.5 m/s, how long does it take the boat to make a round trip consisting of a 250 m displacement downstream followed by a 250 m displacement upstream?

Answer 1

timetotal=timedown+time up
= 250m/(10.5m/s)+ 250/(3.5m/s)