How can I bring my enemy’s grades down or bring my grades up

Before anybody jumps me, I want to clarify that this person is a “friend” of mine and this girl always tried to one up everything. Whenever I make plans I can’t just do it. Recently she tried to learn god knows which grade’s math since I mentioned ONCE and she forced herself to study that..she is also egoistic and “victim” in every situtation so I need tips.