Mighty Bright Window Cleaners' monthly income statement at several levels of activity is as follows: 1,000 2,000 3,000 $ 3.000 $ 6,000 $ 9.000 Windows washed Sales revenue Cost of goods sold Gross profit 1,200 2.400 3,600 1.800 3,600 5,400 Operating expenses Advertising expense 400 400 400 Salaries and wages expense 700 900 1.100 200 200 200 Insurance expense Postage expense Total operating expense 400 800 1,200 1.700 2.300 2.900 + Operating income $ 100 $ 1,300 $ 2,500 (a) Identify each expense as fixed, variable, or mixed. Cost of goods sold Advertising expense Salaries and Wages expense Insurance expense Postage expense (b) Prepare a contribution margin income statement based on a volume of 2.500 windows. (Round unit cost to 2 decimal places, s 52.75 and all other answers to decimal places, s. 5.275) 2.500 windows Per Unit 5 $ 5 $ eTextbook and Media Attempts unlimited SA