Help me quickly! please!!!

A cable pulls a car up a mountain with a force of 4 × 103 N at a vertical constant velocity of 5 m.s-1. It takes 5 minutes to reach the top.

(a)How much work is done in getting the car to the top?
(b)How much work would have been done if the vertical speed was 2,5 m.s-1?
(c)Calculate the power exerted on the cable car in those 5 minutes.