I am trying to count the difference between two fields which are date/time to
show if we met our service level agreements. However, I don't want to count
non business hours.

Business Hours are 8-5.

For example

Cell G3 is the date customer wants to close the deal - 6/23/2008 9:00 AM

Cell I3 is actual closing date 6/23/2008 10:45 AM

I would expect to see (1:45)

Can anyone help? Thanks!