Сalculate the number of days in a week for the last month

[DimaMD]

Hello Community
My task is the following, I have the current month of September, I need to count the number of days of the week (Mondays, Tuesdays, Wednesdays, Thursdays, etc.)
My calculation measure for the current month is :

DaysInWeek = 
    CALCULATE(
    COUNTROWS('Dates'), 
    'Dates'[Number_month] = MONTH(TODAY()))

 I am interested in what will be the measure for calculating these days for the previous month
When I add -1 to MONTH(TODAY()) -1 it doesn't give me the desired result.
Help to understand how to calculate it.

[DimaMD · Accepted solution]

I managed to write a measure that gives me my desired result. I am attaching the file for further reference

[ChiragGarg2512]

Hello @DimaMD, I am unable to understand the issue.

I downloaded the file attachment and the dax was working correctly and giving the number of days in Month(Today()) - 1, i.e., August. 

[DimaMD]

Hi, @ChiragGarg2512  This is how it works if there is no date slicer, I incorrectly indicated the essence of the calculation, my task is to show the number of days of the week when choosing the minimum and maximum date in the slicer, the measure should show the number of the past month.
I managed to write such an event, but for some reason it does not work