I require help calculating the "Salary & Wage portion of the income statement. If you could show your steps on how you obtain the answer, I'd greatly appreciate it.

Please refer to attached document for reference.

Mighty Bright Window Cleaners' monthly income statement at several levels of activity is as follows: Windows washed Sales revenue Cost of goods sold 2,000 4,000 6,000 $ 3,000 $ 6,000 $ 9,000 1,200 2,400 3,600 Gross profit Operating expenses Advertising expense Salaries and wages expense Insurance expense Postage expense Total operating expense Operating income $ 1,800 3,600 5,400 400 700 200 400 400 900 200 800 400 1,100 200 1,200 1,700 2,300 2,900 100 $ 1,300 $ 2,500 (a) Identify each expense as fixed, variable, or mixed. Cost of goods sold Advertising Salaries and Wages Insurance Postage variable fixed mixed fixed variable (b) Prepare a contribution margin income statement based on a volume of 3,000 windows. (Round unit cost to 2 decimal places, e.g. 12.25 and all other answers to 0 decimal places, e.g. 45,000.) 3,000 windows Per Unit $ $ 4,500 Sales Revenue 1.5 Variable Expenses : Cost of Goods Sold 1,800 .60 Salaries Expense Postage Expense 600 .20 Total Variable Expenses .90 $ Contribution Margin Fixed Expenses Advertising Expense 200 Salaries Expense Insurance Expense 200 Total Fixed Expenses $ Operating Income