Cinturon Corporation produces high-quality leather belts. The company's plant in Boise uses a standard costing system and has set the following standards for materials and labor: Leather (3 strips @ $4) $12.00 Direct labor (0.75 hr. @ $12) 9.00 Total prime cost $21.00 During the first month of the year, Boise plant produced 92,000 belts. Actual leather purchased was 287,500 strips at $4.80 per strip. There were no beginning or ending inventories of leather. Actual direct labor was 79,500 hours at $13.00 per hour. Required: Break down the total variance for labor into a rate variance and an efficiency variance using the columnar and formula approaches.