The loaded coaster has a mass of 2000

Question

kg. The starting point of the run (B) is 25 m above point A; the run from B to C is 120 m long,
the run from C to D is 150 m. At D, brakes are applied, bringing the coaster to a halt X m further
along, at E. The average frictional force between B and D is 500 N. Find (a) the work required
to raise the cart to its starting point B (assume velocity at B is ~ zero); (b) the speed of the roller
coaster at D; (c) if the average braking force applied between D and E is 50 kN, what is X?