Calculations Based off A Field Parameter Selection

I have table visual that displays line times with a value columns for "Actuals" and a Field Parameter for two different types of budgets. Next in the visual I really want variance (Actual - Budget) and Variance % (Actuals/Budget -1) as the next two columns in the table. However I want the two variance columns to calculate based on the Budget field parameter selected. Is there a clean way to do this. I don't want to show want budget type, but accidentally show a variance on another budget type. I even tried using the field from the field parameter in the variance calculations but that did not work.

Any clean simple ideas?

Thanks
Alan