Average sales per week

Hi experts,
I have a table I use for sales reports but now I am having trouble creating new feature.
I need to have an additional column to see average WEEKLY sales per sales employee.
What I need is located in DO NOT TOUCH tab - date, sales employee, document total.
Formulas are last option but so far I have no alternatives. I was trying to do it myself - in DO NOT TOUCH tab you will see some formulas. Value I get while calculating AVERAGE PER WEEK PER SALES EMPLOYEE is not correct as it takes all values not unique only.
Can you please help me with it?

I think all you need to do to get the sales/week is take your "SUM PER WEEK PER SALES EMPLOYEE" and divide it by "Week Number". I don't entirely understand what you are asking, so let me know if this is what you are looking for.