In a report I need to calculate a total amount spent for a time period (a quarter) and the remainder available for the rest of the year. If I’m creating a report for the first or the last quarter, then there's no problem: simply subtract the amount spent from the amount budgeted for the year. The result is what’s left for the rest of the year. For the second and third quarters, I need to add the amount spent for past quarter(s) to what was spent for the quarter covered by the report and then subtract that amount from the amount budgeted. How do I do that?