It’d be easier to pivot your data in an ETL and then use a formula tile or beast mode to calculate the difference between the two column values.
@GrantSmith , I tried doing that but it was just not as straightforward as I expected,what should I have in
Step 3 : Name a new column to create
Step 4: What label identifies the rows that belong to this column
Step 5: Select what values will populate this new column