Insert Total and Average rows in a table

I have been ranking my brain about to calculate totals for some columns as well as the Average, the current Matrix version doesn't have an option to tell the matrix not calculate for any specific columns, also calculate a averega Row, as the screenshot shown, wel I need a way to get a the foot of the matrix, two lines, one to show the total for a specific columns, in this example Sales and Purchases, there are more columns that I don't wnat to get a total, also I need a second row that will math the average of those columns, I built some measures on the power bi desktop side and they can not be mover to the Power Query, jsut let me know if I can built on the power bi side like the screenshot shown