Block on inclined plane

Block sliding down an inclined plane

A block slides down an incline (see the fig. in the attachment). As it moves from point A to point B, which are 6.6 m apart force F acts on the block, with magnitude 3.3 N and directed down the incline. The magnitude of the frictional force acting on the block is 6.1 N. If the kinetic energy of the block increases by 28 J between A and B, how much work is done on the block by the gravitational force as the block moves from A to B?