Duration in Hrs/Mins between time stamps, minus off hours/weekends

Here’s what I need, if someone would be so kind as to assist…

I have a Submitted at column which tags the date/time the record was created from a form entry.
I have a Completed column which tags the date/timestamp when the Completed box is checked, which concludes the job duration.
And I have a Duration column which has the following formula:

DATETIME_DIFF({Completed},{Submitted at},'minutes')/60

We work 7am-4pm, M-F… What I need is that duration field to exclude off hours, before 7am, and after 4pm, to get a true measure of the work hours that job took.

Any help would be greatly appreciated!