That was my question. Why am I getting 3?

Does anyone know how Oracle's PL/SQL handles subtraction with a negative number? Really what I need to know is, given the following: (NOTE: this is NOT the code I'm working with. It's just an example...

Ok, so I'm learning about procedures and functions in Oracle and I'm stuck here with my procedure. I have the function part down pretty good, but the whole returning variables with procedures through...