How do I count Weekdays only in a range of dates? Exclude Holidays, weekends.

Hello, I need to make an excel sheet that counts business days only. Not Holidays or weekends.

My excel sheet is attached:

Column D tells me the number of days between Column B and C.
Column F tells me the number of days between Column C and E.
Column H tells me the number of days between Column E and G.
Column J tells me the number of days between Column G and I.
Column L tells me the number of days between Column I and K.
Column N tells me the number of days between Column K and M.
Column P tells me the number of days between Column M and O.
Column Q tells me the total number of days between Column B and O.

But this is counting the weekends and holidays. I do not want it to count those.

Column S and T has the Holidays that we have off at my company-I do not want them counted. I just want to count the business days.
Column V and W has the dates and days(Monday, tuesday, etc) in case it is needed for the formula.

So what formula do I need to put in Columns D, F, H, J, L, N, P to get the number of business days? Any help is greatly appreciated.