Translating where clause or statement in SQL to Power BI

CNENFRNL 

Thank you so much for this. I tried building on your DAX code but got stuck again. Please allow me to expand a little further.

To recap:

This is what I get from the where clause

WHERE (P.APPLYDATE BETWEEN @STARTDATE AND @ENDDATE
OR P.ISSUEDATE BETWEEN @STARTDATE AND @ENDDATE)

My goal is to get an average of the sum of the PR_TIME_DAYS based on COMPLETEDATE. 

And this is what I have done so far:

Using the code you shared with me, I am able to get the count of COMPLETEDATE, which is 5.

The question now is how do I get the sum of the PR_TIME_DAYS based on the 5 rows, which is supposed to 20.

Thanks!