Having trouble graphing my functions

I attached the file that I am having issues with. I am trying to plot three of my functions onto a single graph but right now they arent working. I think there is a problem with the input variable that I am using. I also don't know how to get three functions to plot on one graph. I've also attached a pdf with an example problem that shows roughly how the graph should look along with the funcitons used. My circuit is different which is why some of the functions may look different.