1 hour = 60 min
3/4 hour = (3/4)*60 min
3/4 hour = 45 min
So 8 3/4 hr = 8 hr + 3/4 hr = 8 hr + 45 min
Now add the two times (8:30 and 8 hr, 45 min)
1
8:30
+ 8:45
-------
17:15
which translates to 17:15 - 12:00 = 5:15 pm
So she finished work at 5:15 pm