Capacity Calculation

I am trying to calculate total hours for each week by dividing total hours into 8 hour allotments and then calculate totals by week ending on Friday. I have been unsuccessful using IF functions with NETWORKDAYS. I have put in the values I need in yellow with no formulas. The finish date is actually calculated by a database I use and excludes weekends so I know when it needs to be complete. I need to find out how many hours of a job are allocated to each week if split by a weekend. Anyone got any ideas?