A 91.5 kg man pushes a crate 6.25 m up a ramp that makes an angle of 18.5 degrees with the horizontal.  He exerts a force of 475 N on the crate, parallel to the ramp, and the crate moves at a constant speed.  Calculate the work, in Joules, that the man performs to cause himself and the crate, to move up the ramp.