Nikul runs exercise classes at his local, gym, and gets there each day by train and bus. Classes start at different times each day, but his first class of the day is always either at 9:00, 9:30 or 10:00. He always gets to the railway station 45 minutes before he is due to start teaching and the train journey takes 20 minutes, after which he takes a bus to the gym, which takes 10 minutes. Trains leave every 20 minutes, starting on the hour, and the buses also leave at regular intervals. Some days Nikul find that he gets to work 5 minutes early. All the other days he finds that he gets there 5 minutes late. What possible departure times for the bus could explain the times that Nikul arrives at the gym