a car of mass 3000kg wil just run down a slope of inclination sin-1(1/20) under its own weight.assuming constant resisting forces and a constant tractive force due to the engine determine the power developed when a speed of 15 m/s is attained from rest in a time of 4 mins,when moving on a level road.

I can't work this out.can anyone explain it?

Do I need the slope part at all?

This is a work,energy and power question.