Yes that is correct.

(B) No math major ate pizza last Thursday. M Ç P=Ø

Yes, that is correct.

(C) Some math majors did not east pizza last Thursday. I am not sure how to accurately write this answer.

The set of math majors is NOT a subset of the set of the set of students who ate pizza last Thursday.

(D) Those computer science majors who did not have a test on Friday ate pizza on Thursday. I am assuming this is the answer: CSÏTÍP

That is nonsense! T is a set of students and CS is not a student. Even if x were a student such that , that is a statement, not a set and so cannot be a subset of P.

Again, you cannot use between two of these sets. I think you mean .(E) Math or computer science majors who ate pizza on Thursday did not have a test on Friday. Again I am assuming: MÎCSÍPÇT