East Mullett Manufacturing earned operating income last year as shown in the following income statement:

Sales ...............$531,250

Cost of goods sold ......... 280,000

Gross margin ........$251,250

Selling and administrative expense .... 187,500

Operating income ....... $ 63,750

At the beginning of the year, the value of operating assets was $390,000. At the end of the year, the value of operating assets was $460,000.

Required:

For East Mullett Manufacturing, calculate:

1. Average operating assets

2. Margin

3. Turnover

4. Return on investment