Answer:
E = 15680 J
Step-by-step explanation:
We have,
Mass of Danielle is 80 kg
He is at the top of hill at a height of 20 m
As she slides down at the bottom of the hill, its potential energy gets converted to its kinetic energy. So, the kinetic energy at the bottom of the hill is :

So, she will have 15680 J of kinetic energy at the bottom of the hill.