"And then you apply the rule, which in this case, is dividing by seven-"

donnie was helping you with math homework, not because you don't understand it, but because he LOVES the stuff! He seems to be enjoying himself explaining basic algebra to you, and you don't have the heart to tell him that you already knew the answers. It was funny seeing your best friend having fun. Even if he is doing one of the most hated school subjects in existence.