how do you get to 40000 U?

Question 15 Frekko Company provided the following information: Standard costs per unit: Variable overhead Fixed overhead 4 mach, hrs @ $6/mach hr 4 mach. hrs. @$10/mach hr Actual units produced 20.000 units Normal capacity in units 21.000 units Actual machine hours 79.000 machine hours Actual variable overhead cost $540,000 Actual fixed overhead cost $810,000 Using the two-variance method, what is the volume variance? $6,000 F $40,000 F $6.000 U $40.000 U