When I studied for my MSc is correct because MSc or MS (Master of Science) is a degree and you study for a degree.
The rest of sentence 2 should read: I got at least 65 points (or at least a 65) on the Accounting A and B exams (or on the exams in Accounting A and B).
got: a common substitution for received in this context
a 65: a kind of shortand for a score of 65 points, common in this context
the word subject is not necessary because it is clear from the context
(in US English: on the exam, on the test, on the quiz)
Student or Learner