I Still Have My Black Pointy Hat from Halloween

Any guesses as to what might be going on here?

I am greatly distraught the grade witch appears on [the online grade system] is not at all what i was expecting. i know on the 2nd and 4th exams i made an 86 and 90 so i am very confused on how i ended up with a D please please please if you could look over my work again.

[Hint: Consider the scores on the first, third, and final exams.]