TOPN with filters?

I have a query - recordId, department, date and a calculated column (number of business days minus holidays and weekends using a database function). Each department may have different recordId for the same date. 

Perhaps I'm overthinking it - I am creating a card that shows the number of businessdays for each department with the earliest date, just 1 of any recordId(s). 

So far,

1) Change businessdays summarization to Don't summarize. 

2) I have created 1 measure that looks for MIN date for each departments.

HRMinDt = CALCULATE(MIN('Query'[Date]), FILTER('Query','Query'[Department]="HR"))

3)  also 1 measure for TOP1ID = TOPN(1, VALUES(Query[RecordID])

The idea was to get businessdays value for the recordID (filtered by measure #2 - TOP1ID) and min date for department (filtered by measure #3). 

Before that, I have tried the following without success:

Error: The expression refers to multiple columns. Multiple columns cannot be converted to a scalar value.

Any suggestions are appreciated. Feel free to correct me if I'm overthinking it.