Grass Pad's variable overhead is applied on the basis of direct labor-hours. The standard cost card for product AB90 specifies 8.4 direct labor-hours per unit of AB90. The standard variable overhead rate is $5.60 per direct labor-hour. During the most recent month, 800 units of product AB90 were made and 6,800 direct labor-hours were worked. The actual variable overhead incurred was $41.140. Required: a. What was the variable overhead rate variance for the month? b. What was the variable overhead efficiency variance for the month