Answer:
a. 14:45pm (It's really easy to convert to a 24-hour clock time, all you need to do is add 12 hours onto the hour. Eg. 2 + 12 = 14 so it will be 14:45.pm
b. The length of time between 11:45am and 2:45pm is 3 hours.
I don't know what c is sorry.
Hope that helps. x