Router Enterprises reported total assets at December 31 totaling $78,600. The following selected amounts were taken from the company's financial statements for its year ending December 31: Retained earnings $45,600 Sales $170,000 Accounts receivable 3,500 Common stock 10,000 Notes payable 8,000 Net income 15,000 How much is the company's shareholders' equity as of December 31? Select one: a. $70,600 O b. $48,000 O c. $28,000 d. $22,500