Could someone please explain how you get this answer???

Question

A skier with a mass of 60.0 kg pushes off with a horizontal speed of 3.0 m/s from the top of a snow covered hill. As he slides down the hill, his height decreases by 42 m over a distance of 100 m of travel. How much will his kinetic energy increase by the time he reaches the bottom of the hill (assuming no friction)?

Answer 1

Change in Ke is equal to the loss of potential energy
m g h = 60 * 9.81 * 42 Joules