need help excluding holiday weeks

[Daman861]

I work for a company that pays based on performance so keeping track of my numbers is essential one of the things I need to keep track of is a 13 week running average of my weekly revenue that would be easy but the company excludes weeks that have holidays because that would make the week shorter and hurt my running average so I need a formula that will run an average but exclude weeks with holidays and average with that appropriate number ie if the 13 week has one holiday week it would divide the total by 12 instead of 13 and I need it to determine this by looking at the date of Monday for that week I'm only good at the basics when it comes to formulas but I have to search for something that works when it gets to advanced