I think it goes a little like this:
Then it's separation of variables or integrating factor to get an equation for v in terms of t.
A particle of mass m is released from rest at time t = 0 at some height above the ground. It experiences a resistance mkv where v is its speed and k a constant. Find v and the vertical distance fallen after time t.
I admit I am a little lost on this question, so any help would be appreciated.