Hello gentleman

Girl I know in school called R. Two years younger than me. Had a bit of flirty chat but I fucked up due to beta behaviour at the time. Don't talk much now. Was sitting with my friends trying to study for a test and I began tapping out a rhythm while doing so. She was next to me and tells me to stop. I tell her to fuck off. This happens a few times and then I get bored and leave.

Get other girl to walk to class we share then R shows up and complains to other girl that I'm rude. I tell her to fuck off again. Girl with me replies that I'm an asshole and that R should deal with it. R replies with 'Who does he think he is? Some sort of mathematician?" (I have a rep for being good with numbers). She laughs at her own joke and walks off.

I had zero reply to this.

What are RP ways to reply to girls who disrespect you?

Also when girls say who do you think you are, is that a shit test? What is the reply?

I am ashamed to say I am too busy holding back the urge to punch them than creating a clever reply.

Thanks.

EDIT: I was the only person studying. It was breaktime and everyone was messing about.