WORKDAY_DIFF return hours and minutes, not whole days


I am having trouble understanding the WORKDAY_DIFF and DATETIME_DIFF. Primarily I need it to return hours and minutes within 5 working days. Not just whole days with the WORKDAY_DIFF and not just total hours and minutes including weekends with DATETIME_DIFF.

Example: Start a project at 4:25 pm Friday and finish at 9:40 am Monday, I would like my Turn Around column to say 2 hours and 15 minutes (2:15). I do not need it to round up to the nearest whole hour.

I would appreciate any help you can give.