The Dinkle and Frizell Dental Clinic provides both preventive and orthodontic dental services. The two owners, Reese Dinkle and Anita Frizell, operate the clinic as two separate investment centers: Preventive Services and Orthodontic Services. Each of them is in charge of one of the centers: Reese for Preventive Services and Anita for Orthodontic Services. Each month they prepare an income statement for the two centers to evaluate performance and make decisions about how to improve the operational efficiency and profitability of the clinic. Recently, they have been concerned about the profitability of the Preventive Services operations. For several months, it has been reporting a loss. Shown below is the responsibility report for the month of May 2014.

		Actual			Difference from Budget
Service revenue		$41,260			$1,140	F
Variable costs:
Filling materials		5,140			150	U
Novocain		3,940			77	U
Supplies		1,890			400	F
Dental assistant wages		2,590