Dave Ryan is the CEO of Ryan's Arc. At the end of its accounting period, December 31, Ryan's Arcade has assets of $628,140 and liabilities of $258,670. 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 $79,430 and liabilities increased by $17,670 during the year