Schlick Framing's cost formula for its supplies cost is $1,940 per month plus $10 per frame. For the month of August, the company planned for activity of 634 frames, but the actual level of activity was 638 frames. The actual supplies cost for the month was $8,680. The activity varlance for supplies cost in August would be closest to: O $400 F O $40 F 0 $400 U O $40 U