It's only fair
Fairness has little basis in reality. It's perception. Not everyone sees things the same. The person in your math-help scenario might have perceived the situation as entirely fair from his point of view: he did something for you, you did something for him. Even if he deliberately did what he did for the specific purpose of extracting a service from you with deliberate intent and forethought, it's possible he might still have seen it as an even exchange. The negative consequences received by you were not his doing. He's not the one who kicked you out.
Nevertheless, you feel you were taken advantage of by this person. And your trusted friend appears to agree. Ok. But it seems to me from your description that
all you had to do was say no.
You were not beholden to this person for having helping you in math. You were not purchased. You could have said no. You could have explained why you were saying no: it meant missing a meeting, so maybe a different time.
But you didn't. Why not? Is it because you perceived "fairness" in doing what he asked? He did something for you, so you felt it would be "fair" to do something for him? If
you saw it that way, why are you complaining about it?
And if you
don't think it was fair, then why did you do it?
Learn to say no.
I felt like a Pack mule
Did you feel like a pack mule because the work was difficult, or because you felt
obligated to do it because he'd done something for you? You were not obligated. If you felt obligated, is that his problem?
At work I thought I had been part time associate. Apparently, I was just seasonal/temporary. Since I'm sure as as heck I was part-time I asked but the manager just said something along the lines of "oh I meant to sit down with you about that but you weren't scheduled.." and "thank you for your service.". That service one still irritates me tbh. Thus job was just retail and I'm only 20 but...ya.
This one sounds like a simple miscommunication to me. "Part time" and "seasonal" are not mutually exclusive. You may well have been part time. That doesn't mean you weren't seasonal.
My mom constantly tries to find reasons to not allow me to go where I want despite having a 3.31 out of 4.0 in college. I know it's just a B but come on..My brother never even attempted college or working after high school. Can't I have the Damn car? It's only fair plus he's the one that gets the tickets not me.
...oh, I see. So...because of what you've done, you feel entitled to have the car. Isn't that interesting? Guy helped you with math so you felt obligated to do something for him, because "that's fair." You received good grades so you felt your mother was obligated do so something for you, because "that's fair."
Do you see how it might be your worldview of "fairness" that's at the root of the issue here?