I wanted to first say that you are NOT stupid. This can be challenging for anyone, and I hope you don't really feel stupid. I'm sure you aren't. Not understanding something does not make you stupid. And reaching out for help when you need it means you're smart.
The volume of a cylinder is like the area of a circle with an extra dimension for height to make it 3-D. We write [tex]V= \ \pi r^2h[/tex], where r is the radius and h is the height.
For this problem, we are asked to use variables for the radius and the height. All you have to do is plug-in the given variables. [tex]V= \pi (r)^2(3r) = 3r^3 * \pi [/tex].
