Calculating time to track work hours

I can't figure out how to do a proper formula for calculating time. For instance I have one column that says "Time In", the next is "Time Out" and the other is "Lunch Time". My calculation needs to be this:

Find the total hours between the Time In and Time Out and then Minus the lunch time to get total hours worked for the day.

The only way I can get this to work is using 24 Hour time format. Is there another way?