1. On the Financial Statement go to the Columns tab
  2. Click New Column
  3. Ensure the "Column Definition Type" drop down is set to Amount
  4. Then select the appropriate fields form the list on the left to add to the box on the right
  5. Underneath the box on the right, you will see options for the mathematical operations
    Column Options
  6. If the operations need to be performed in a certain order, use the parentheses to group operations.
  7. Click OK to save the changes to the new column