Dave Ryan is the CEO of Ryan's Arcade. At the end of its accounting period, December 31 , Ryan's Arcade has assets of $628,150 and liabilities of $260,220. Using the accounting equation, determine the following amounts: a. Stockholders' equity as of December 31 of the current year. b. Stockholders' equity as of December 31 at the end of the next year, assuming that assets increased by $88,770 and liabilities increased by $17,550 during the year