A 65 kg person is just learning how to ski. Starting from rest, the skier slides down a hill of height H = 3.0 m, and ends up moving at 6.0 m/s at the bottom. How much work did the forces of friction and air drag do on the skier? (There are no other forces but friction, air drag, and gravity. Assume the temperature of the skier and skis doesn't change to there is no change in internal energy.) Give your answer in Joules to three digits.