If someone is skateboarding down a hill which type of energy is decreasing

potential energy

you have potential energy when you're stopped. you have kinetic energy when you're moving. so as you're going down a hill, kinetic energy is increasing and potential energy is decreasing.

the cells uses some of the atoms of the glucose molecules to atp molecules. the atoms of the glucose molecules will then be converted into energy which will be eventually stored in atp. the energy produced which are stored in atp are coming from the glucose’s chemical bonds.