I have been asked to make an animation in GeoGebra and I am not sure what variables to use. I am guessing that I need to find the function of the given problem but I am not sure if this is the right direction to go. Here are the instructions:

Before solving the problem, model the way that the variables are changing by creating a GeoGebra animation.

and here is my problem:

The dimensions of the conical tank are a height of 16 ft and a radius of 5 ft. Find the rate at which the surface area of the water changes when the water is 10 ft high if the cone leaks water at a rate of 10 ft³/min

I have the solution for the problem but the instructions suggest to create the animation prior to solving the problem.