Answer:
a) 8:40 am, 8:50 am
9:20 am, 9:40 am
10:00 am, 10:30 am
10:40 am, 11:20 am
11:20 am, 12:10 pm
12:00 pm, 1:00 pm
12:40 pm, 1:50 pm
1:20 pm, 2:40 pm
2:00 pm, 3:30 pm
2:40 pm, 4:20 pm
3:20 pm
4:00 pm
4:40 pm
b)11:20 am.
c)cannot be answered based on the context of the question