You should know that there are:
60 seconds in 1 minute
60 minutes in 1 hour
24 hours in 1 day.
This means that there are:
30 seconds in ½ minute
30 minutes in ½ hour
15 minutes in ¼ hour
45 minutes in ¾ hour
24 hours in 1 day
12 hours in ½ day.