A crate of mass 40 kg is pushed up a ramp by a person as shown in the figure below. The person pushes the crate a distance of 14 m as measured along the ramp. Assume the crate moves at constant velocity. Assume the coefficient of kinetic friction between the crate and the ramp is

Question

A crate of mass 40 kg is pushed up a ramp by a person as shown in the figure below. The person pushes the crate a distance of 14 m as measured along the ramp. Assume the crate moves at constant velocity. Assume the coefficient of kinetic friction between the crate and the ramp is 
μK = 0.35. 
Angle between the horizontal and the ramp &=30°
 Find the work done by gravity on the crate.

I tried to solve this for minutes but i can't find the right answer