Dave Ryan is the CEO of Ryan's Arcade. At the end of its accounting period, December 31, Ryan's Arcade has assets of $625,660 and liabilities of $246,630. 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 $75,960 and liabilities increased by $18,050 during the year