Solve for ‘X’

Katie Kush and Lily Larimar just can’t seem to focus in class, and professor Maximus isn’t happy about it. To stop their constant chatter, he seats star student David Lee between them to break up the talking once and for all. But after professor Maximus falls asleep at his desk, the students do much more than talk. In the true fashion of a helpful student, David makes sure Lily and Katie ace their math test—and learn a few other things, too.