There are 10 hours and 15 minutes between 7:30AM and 5:45PM.
Since Roger gets a 50 minute lunch break and two 20 minute breaks, we can add all of the breaks together and subtract the total break time from his work time.

Convert 10 hours, 15 minutes into minutes. There are 60 minutes in an hour.

Subtract the total break time from the total minutes during Roger's work day.

Convert this number into hours and minutes.

R45 represents the minutes.
Roger works
8 hours and 45 minutes every work day.