2-24 Cost behavior identification; contribution format income statement (LO 1, 3) Mighty Bright Window Cleaners' monthly income statement at several levels of activity is as follows: Windows washed Sales revenue Cost of goods sold Gross profit Operating expenses 1,000 2.000 3,000 $3,000 $6,000 $9,000 1200 2400 3,600 oo0 1,800 $3.6005400 Advertising expense 400 400400 Salaries and wages expense 700 9001,100 200 200 200 800 1,200 Total operating expenses 1,700 2,300 2,900 200 90o 400 Insurance expense Postage expense Operating income $ 100 $1,300 $2.500 Required a. Identify each expense as fixed, variable, or mixed. b. Prepare a contribution margin income statement based on a volume of 2,500 windows