I want to add a column in the power bi matrix visual to calculate the average of the sum of columns. the column displays the count of items. please assist.

I tried to create Dax measures but that did not work. in my table, there are 6 columns that shows the counts of items, i want to add those numbers and divide by 6 to calculate their average. The table has more than 10 rows and i want average for each row. The average should change per date selection.