Dure Corporation's cost formula for its selling and administrative expense is $24,500 per month plus $1 per unit. For the month of July, the company planned for activity of 7,200 units, but the actual level of activity was 7,160 units. The actual selling and administrative expense for the month was $31,460. The activity variance for selling and administrative expense in July would be closest to:

240 F

40 F

40 U

240 U