Suman goes to school at 6:00 AM  and return back home at 4:45 PM . Now let me ask u a question how much does she spent at school?

Given :  Time at which Suman goes to school  =  6:00 am  =  6:00

 Time at which Suman return back to home =  4:45 pm

 =  (12:00 + 4:45)

 =  16:45

Thus,  the time Suman spent in school is  (16:45 – 6:00) hours

 or  10: 45  hours

 or 10 hours 45 minutes.