Last date of the previous month show on a matrix table

[v_mark]

Good day, 

I am connected through Direct Query and trying to calculate the last date of the previous month for my beginning inventory.  The goal was to get all the tickets open at a specific point in time and the close date is NULL and have it viewed on a matrix table. Like this one below. 

Month - Year	Begin Inventory #	MTD Inventory #
Jan - 2021	?	267
Feb - 2021	?	363
March - 2021	?	58

The sample data set is here 

The logic is: 

As of Jan 1st 2021.

Count of all tickets with the status of Open

And the placement date is <=12-31-2020

And the close date is NULL

As of Feb 1st 2021.

Count of all tickets with the status of Open

And the placement date is <=01-31-2021

And the close date is NULL

As of March 1st 2021.

Count of all tickets with the status of Open

And the placement date is <=02-28-2021

And the close date is NULL

Tried to use multiple measurements but it only shows MTD. 

I appreciate all the help 

[amitchandak]

@v_mark , With help from the date table

Try openingbalancemonth -https://dax.guide/openingbalancemonth/

Refer to my video how to use: https://www.youtube.com/watch?v=6lzYOXI5wfo