Bat Company's flexible budget for the units manufactured in May shows $15,640 of total factory overhead; this output level represents 70% of available capacity. During May, the company applied overhead to production at the rate of $3.00 per direct labor hour (DLH), based on a denominator volume level of 5,850 DLHs, which represents 90% of available capacity. The company used 5,000 DLHs and incurred $16,600 of total factory overhead cost during May, including $5,600 for fixed factory overhead.

What is the total factory overhead flexible budget variance for Bat Company in May?