For question one:
First class goes from 8:00 to 9:00 second class starts 10 mins later at 9:10 and goes to 10:10. Ten minute break again 3rd class starts at 10:20, goes to 11:20. 10 min break again, fourth class starts 10 mins later at 11:30 and goes to 12:30. The answer for 1 is 12:30
