Pearse Kennel uses tenant-days as its measure of activity; an animal housed in the kennel for one day is counted as one tenant-day. During December, the kennel budgeted for 3,500 tenant-days, but its actual level of activity was 3,480 tenant-days. The kennel has provided the following data concerning the formulas used in its budgeting and its actual results for December: Data used in budgeting: Fixed element per month Variable element per tenant-day Revenue $30.00 Wages and salaries $2,500 $6.00 Food and supplies 700 10.80 Facility expenses 7,500 3.00 Administrative expenses 7,300 0.60 Total expenses $18,000 $20.40 Actual results for December: Revenue $107,280 Wages and salaries $23,450 Food and supplies $36,785 Facility expenses $19,200 Administrative expenses $9,130 The net operating income in the planning budget for December would be closest to: $18,715 $18,621 $15,600 $15,408