Please help and show work, cannot figure out

Cooney Inc. reported net income of $540,000 during 2017 and paid dividends of $52,000 on common stock. It also has 20,000 shares of 6%, $100 par value preferred stock outstanding. Common stockholders' equity was $2,400,000 on January 1, 2017, and $3,200,000 on December 31, 2017. The company's return on common stockholders' equity for 2017 is: A. 15.0% B. 13.1% C. 19.3% D. 17.4%