Answer:
21:30
Explanation:
The 24hour clock uses 0:00 for midnite. 1am through noon are just 1:00 - 12:00. But the pm hours continue counting up, 13 - 23.
For example, 1pm is 13:00 and 2pm is 14:00.
To change to 24 hour clock, for pm hours, ADD 12.
So for your problem, 9:30 is:
9:30 + 12
= 21:30