Dave Ryan is the owner and operator of Ryan's Arcade. At the end of its accounting period, December 31, Ryan's Arcade has assets of $643,980 and liabilities of $225,610. Using the accounting equation, determine the following amounts: a. Owner's equity as of December 31 of the current year. b. Owner's equity as of December 31 at the end of the next year, assuming that assets increased by $86,620 and liabilities increased by $17,610 during the year