Marvin's Mechanical Repair Shop started the year with total assets of $60,000, total liabilities of $40,000, and retained earnings of $18,000. During the year, the business recorded $100,000 in auto repair revenues, $70,000 in expenses, and the company paid dividends of $15,000. If Marvin's Mechanical Repair Shop ends the year with total assets of $80,000, and total liabilities of $35,000, what must be the amount of common stock issued during the year?