These are 2 physics questions that I cannot get

3. A boy pulls a 28.0-kg box with a 150-N force at 300 above a horizontal surface. If the coefficient of kinetic friction between the box and the horizontal surface is 0.27 and the box is pulled a distance of 22.0 m, what is the net work done on the box? X 1227.95 J Show my other submissions 4. A roller coaster reaches the top of the steepest hill with a speed of 6.60 km/h. It then descends the hill, which is at an average angle of 350 and is 40.0 m long. What will it's speed be when it reaches the bottom? Assume HK = 0.20. X 9.64 m/s Show my other submissions