Hi Eric,

Thats an excellent question. The solution I can give you is by using loop in the flow.

first, add loop element after the Get holidays

second, create a text formula with the following formula

CASE( MOD({!loopHoliday.ActivityDate} - DATE(1900, 1, 7), 7), 0, "Sunday", 1, "Monday", 2, "Tuesday", 3,

"Wednesday", 4, "Thursday", 5, "Friday", 6, "Saturday","Error")

third, add a decision and assignment element that basically add 1 the holidaycounter if the formulafield is does not equal Sunday and Saturday and Error.

But things to consider here, is you should consider that flow has iteration limits, that you will eventually hit in the next 5 - 10 years (hopefully salesforce increase the limit by that year)

thanks