Company K manufactures chairs and budgets to make 21,000 units per month; variable labour costs for these units are budgeted as follows: total labour hours 2,100 hrs @ an hourly wage of $20. For the month of June, the actual results were 22,500 units made using labour hours of 2,475 and labour costs totaling $49,500. For the month of June, calculate the efficiency variance for labour (i.e. Level #3) $7,500 U $4.500 U $4.500 F $7.500 F