During 2016, Linda, Inc.'s net income was $1,400,000. Its common stockholders' equity was $2,160,000 at January 1, 2016 and $3,440,000 at December 31, 2016. During 2016, Cooper had 10,000 outstanding shares of 6%, $300 par value cumulative preferred stock. During December, 2016, Linda's board of directors declared the annual preferred stock dividend and a $240,000 common stock dividend. What is Linda's 2016 return on common stockholders' equity?