The following standards for variable manufacturing overhead have been established for a company that makes only one product:

Standard hours per unit of output - 7.8 hours

Standars variable overhead rate - $12,55 per hour

The following data pertain to operations for the last month:

Actual hours - 2,900 hours

Actual total variable manufacturing overhead cost - $36,975

Actual output - 2100 units

What's the variable overhead efficiency variance for the month?