How many computers in the classroom?

Barbara: Excuse me. Are you in charge here?
Assistant: Yes. Sort of.
Barbara: Then perhaps you can help me. I need to use a computer to type an assignment. What do I have to do?
Assistant: Well, are you a student?
Barbara: Yes, 1 am. First year.
Assistant: OK. Have you used a computer before?
Barbara: Yes. I’ve done a bit of word processing.
Assistant: That’s good. That’ll save you a lot of time. Well, there’re 36 computers in this suite and they’re all available for student use. Staff is not supposed to use the computers in this room. The computers are in constant demand so you’ll need to book well in advance. OK, now, here’s a timetable and booking sheet. It’s in that book which is kept just inside the door here. You can reserve a computer for 2 hours at a time. If no one else has reserved it after that you can continue past your booked time, but you must be sure that won’t happen very often. And the computer room is open from 8:00 in the morning to 10:00 at night from Mondays to Fridays and on weekends and public holidays from 9:00 to 5:00.
Barbara: Mm. What do I do if something goes wrong with the computer?
Assistant: There’s usually someone here at least from 9:00 in the morning most days in case something goes wrong. So you’ll really only have a problem if you’re here before 9.