Get value from previous rows in same table?

I have a table I want to show to executives called "Reporting Table". Its connected to raw data, and the raw data has lots of facets the executives will slice by in PowerBI.

Report Table...

Raw Data...

I want to customize the value shown in the Total row of report table to be the "a" row minus the "b" row multiplied by the "c" row, but I want all the facet filters to still work, so I don't really want to "blow away all my existing filters" to perform the calculation. I also want the two tables to be connected ,so that drilldown will work. Ideas?