A 64kg skateboarder on a 2.0kg skateboard is on top of a ramp with a vertical height of 5.0 m what is the skateboarders maximum kinetic energy at the bottom of the ramp

The formula for a kinetic energy KE of a falling body is

KE = mgh

where m = mass, g = acceleration due to gravity (9.8 m/s^2, constant), h = height.

The total mass of a skateboader and a skateboard is 64 + 2.0 = 66 kg.

Finally,

KE = 66*9.8*5.0 = 32340 J