hi anyone can help me on this?

(a) A 3 ton vehicle travels along a horizontal road at 50km/h against a tractive resistance of 150N per ton. Calculate the braking force needed to stop the vehicle in 50m

(b) This vehicle now rolls downhill from rest along a slope of 1 in 20 from a distance of 200m. What is then the velocity assuming the same tractive resistance.

(c) If a braking force of 3kn is then applied. Calculate the distance travelled before coming to rest.

i tried to do this question and not sure bout the answers.

Ans (a) = 1022N

Ans (b) = 11.622

Ans (c) = don't know what to do??

pls can someone help? its really urgent!! =(