Dave Ryan is the CEO of Ryan's Arcade. At the end of its accounting period, December 31, Ryan's Arcade has assets of $648,800 and liabilities of $245,360. 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 $75,060 and liabilities increased by $18,970 during the year