Please show work

Biery Corporation makes a product with the following standard costs: The company produced 4,100 units in April using 5,380 liters of direct material and 2,610 direct labor-hours. During the month, the company purchased 6,000 liters of the direct material at $5.80 per liter. The actual direct labor rate was $19.80 per hour and the actual variable overhead rate was S2.90 per hour. The company applies variable overhead on the basis of direct labor-hours. The direct materials purchases variance is computed when the materials are purchased. The labor efficiency variance for April is: $2,850 F $2,850 U $2,970 F $2,970 U