Difference between two columns in a matrix

Trying to work out the difference between two filtered columns in a matrix visual. The report is here: https://app.powerbi.com/view?r=eyJrIjoiYTMzOWE3NjMtNzY4OC00MWNiLTliZTYtYTNjZjg1OGUzMmQ2IiwidCI6I...