We have that Marty teaches three classes a day, and each class has fewer than 8 students. Let's suppose that each class has 8 students, in this case we have that the total number of students that Marty teaches is x = 3×8=24, because Marty teaches three classes a day and x represents the total students Marty has in a day. But we know that each Marty's class has fewer than 8 students and not exactly 8, then we should have x<24. Because a good case for Marty would be to have 8 students in each class.
