I'm mostly confused on Part B

Sunland Window Cleaners' monthly income statement at several levels of activity is as follows: (a) Identify each expense as fixed, variable, or mixed. (b) Prepare a contribution margin income statement based on a volume of 6.400 windows. (Round unit cost to 2 decimal places, eg. 52.75 and all other answers to 0 decimal places, eg. 5,275.) Fixed Expenses Advertising Expense Salaries Expense Insurance Expense Total Fixed Expenses Operating Income