Preble Company manufactures one product. Its variable manufacturing overhead is applied to production based on direct labor-hours and its standard cost card per unit is as follows:

Direct materials: 5 pounds at $11 per pound	$	55
Direct labor: 3 hours at $12 per hour		36
Variable overhead: 3 hours at $7 per hour		21
Total standard cost per unit	$	112

The planning budget for March was based on producing and selling 21,000 units. However, during March the company actually produced and sold 26,600 units and incurred the following costs:

1. Purchased 154,000 pounds of raw materials at a cost of $9.50 per pound. All of this material was used in production.

2. Direct laborers worked 63,000 hours at a rate of $13 per hour.

3. Total variable manufacturing overhead for the month was $510,930.

Q.What is the labor efficiency variance for March?

Please explain it step by step