I'm trying to figure out how to get this formula to return a zero if the Age of Closed cases and the count of closed cases is both "0".
=IFERROR(SUM([Age of Closed Cases]@row, [Age of Active Cases]@row) / SUM([Count of Closed]@row, [Count of Active]@row), 0)
Both are derived from a =COUNTIF that uses a cross sheet reference to count the active and closed cases every month.