Jake's Roof Repair has provided the following data concerning its costs:

Fixed Cost

per MonthCost per

Repair-HourWages and salaries$20,600$15.00Parts and supplies$7.10Equipment depreciation$2,760$0.30Truck operating expenses$5,750$1.70Rent$4,620Administrative expenses$3,890$0.50

For example, wages and salaries should be $20,600 plus $15.00 per repair-hour. The company expected to work 3,000 repair-hours in May, but actually worked 2,900 repair-hours. The company expects its sales to be $45.00 per repair-hour.