I hav a huge problem.
On of my course marks is considerably low, but that's not bcus I was bad in the subject. Correctly calculating my mark, I would hav gotten 10% higher which would a decently good grade. However, due to the "system" the marks were entered, it made it so that the first quiz would b weighed a lot (which was the quiz I did horribly on).
But because of that stupid system (which I'm sure none of the other courses hav) my grade for this course is very low and wats worse is that I don't even deserve this grade. I explained to the teacher how the calculations were wrong and how this would affect my university application, as it would b seen in the first report card along with the uni application.
But she says "it's just the system" and may not even change my mark to the right one. I rlly want to die or kill her...mostly die..
What should I do?

mostly if that doesn't work out with your lecturer, just inform a higher authority about your situation. If you can't, you might have to resit the quiz or retake the whole course again depending on the terms of your uni.

I wish you best of luck

If you can't get it changed (talking to someone of high authority or an academic advisor is always the most efficient way to accomplish that), and haven't done your personal easy on the application yet, figure out how to incorporate your experience into your essay. If you have a bad grade or two, universities like you to explain those bad grades. If the majority of your grades are good, you shouldn't have to worry too much. Universities look at your entire transcript to see the trend of your grades.

Perhaps write a formal complaint, or talk to someone who can help you make the appeal.

cheers.