East Mullett Manufacturing earned operating income last year as shown in the following income statement: Details An account shows the following information: Sales $3,750,000, Cost of goods sold 2,250,000, Gross margin $1,500,000, Selling and administrative expense 1,200,000, Operating income $300,000, Less: Income taxes (@ 40\%) 120,000, Net income $180,000 At the beginning of the year, the value of operating assets was $1,600,000. At the end of the year, the value of operating assets was $1,400,000. Refer to the information for East Mullett Manufacturing above. Round answers to two decimal places. Required: Calculate (1) average operating assets, (2) margin, (3) turnover, and (4) return on investment