You are his best friends (Niccolo) sister (your name).

One day, you and Niccolo were walking into your math class with your sister (Camilla). When you enter the classroom, found out that you had a new teacher. And a new seating plan! Niccolo is sat next to Camilla and you are sat next to Brando

The lesson starts and Brando is bad at math so he doesn't understand it. You're doing algebra. You understand it very well so you decide to help him.