Willis Corporation manufactures industrial-sized gas furnaces and uses budgeted machine-hours to allocate variable manufacturing overhead. The following information pertains to the company's manufacturing overhead data: Budgeted output units 30,000 units Budgeted machine-hours 10,000 hours Budgeted variable manufacturing overhead costs for 15,000 units $322,500 Actual output units produced 44,000 units Actual machine-hours used 14,400 hours Actual variable manufacturing overhead costs $484,000 What is the flexible-budget variance for variable manufacturing overhead? a. $11,000 favorable b. $11,000 unfavorable c. $8,600 favorable d. None of these answers is correct.