Matter-of-Fact Medicine uses client-visits as its measure of activity. During September, the business budgeted for 2,100 client-visits, but its actual level of activity was 2,140 client-visits. The business has provided the following data concerning the formulas used in its budgeting and its actual results for September: Fixed element per month Variable element per client-visit Revenue $44.50 Personnel expenses $26,100 $12.60 Medical supplies 600 7.2 Occupancy expenses 6,500 2.4 Administrative expenses 3,100 0.1 Total expenses $36,300 $22.30 Actual results for September: Revenue $93,240 Personnel expenses $50,754 Medical supplies $15,238 Occupancy expenses $11,646 Administrative expenses $3,394 The spending variance for medical supplies in September would be closest to: (F: favorable, U: unfavorable)