Question

Can someone give me a step-by-step process on how to solve this? I know the answer I just need to know how to do it for a test:


A man wishes to row the shortest possible distance from north to south across a river which is flowing at 2 km/hr from the east. He can row at 3 km/hr.
(a) In which direction should he steer?
(b) Suppose that when the man is in the middle of the river, a wind of 6 km/hr from the southwest starts.

In which direction should he steer to move straight across the river?