Being a public institution, you should be able to find the budget or an audit report for your university. This should have (projected in the case of the budget) expense and revenues, including tuition, donations, hotdog sales, etc.
Now here's the tricky part: if your university is like mine, there are some high-profile donors that give not-inconsiderable donations. However, their dollars go into capital funding (for new buildings, new extensions, statues, etc.) rather than operating funding (salaries, maintenance, photocopying, utilities, etc.) And you can't borrow from Carl to pay Ollie (capital for operating). And sometimes their dollars force an increase in operating funding from general revenues because you suddenly have new buildings to take care of.
So keep that distinction (capital vs. operating vs. sometimes research) in mind when you're reading through the document, and that you're looking at two or three separate budgets that just happen to be reported simultaneously in the same place.
I'm given to understand that for every undergrad dollar that comes in for operating costs, us Canadians have the provincial government chipping in $3 to $10. For you Americans, the ratio used to be the same, but is now flipped around (again, from what I understand).