Stone Industries uses flexible budgets. At normal capacity of 16,000 units, budgeted manufacturing overhead is: $48,000 variable and $270,000 fixed. If Stone had actual overhead costs of $321,000 for 18,000 units produced, what is the difference between actual and budgeted costs? $3,000 unfavorable $3,000 favorable $9,000 unfavorable $12,000 favorable