Calculate Total Gate Pass Time in C#

Question

Break Time Start : 11:45 AM

Break Time End : 12:45 PM

 

Gate Pass Calculation Total Time

Start Time	End Time	Total Time
9:00 AM	10:00 AM	1 Hour
11:00 AM	12:00 PM	45 Minutes
11:30 AM	12:45 PM	0 Hour and 0 Minute
12:30 PM	2:30 PM	1 Hour 45 Minutes

 

How can I calculate total gate pass time with subtract break time?

Anybody help me?