SkiTwin Corporation uses a standard cost system to assist in its manufacture of water skis and uses direct labour hours to apply its overhead. The company controller provides you with the following information on the results of its most recent year end. Budget Actual Units produced 100,000 99,000 Units sold 100,000 96,000 Direct materials 50,000 kgs 47,840 kgs Direct labour 40,000 DLHs 37,720 DLHs Production costs: Direct materials $200,000 $207,404 Direct labour $500,000 $471,500 Variable overhead $80,000 $84,640 Fixed overhead $160,000 $162,000 There were no beginning or ending work-in-process inventories but there were 4,000 units of finished goods at the end of the year. c. Calculate the direct labour efficiency variance. I don't know how we get 39,600 on the calculation for this part please help!!!