Kirnon Clinic uses client-visits as its measure of activity. During July, the clinic budgeted for 3,250 client-visits, but its actual level of activity was 3,160 client-visits. The clinic has provided the following data concerning the formulas to be used in its budgeting: Fixed element per month Variable element per client-visit Revenue - $ 39.10 Personnel expenses $ 35,100 $ 10.30 Medical supplies 1,100 7.10 Occupancy expenses 8,100 1.10 Administrative expenses 5,100 0.20 Total expenses $ 49,400 $ 18.70 The activity variance for net operating income in July would be closest to: