Stahl Consulting started the year with total assets of $60,000 and total liabilities of $15,000. During the year, the business recorded $48,000 in catering revenues and $24,000 in expenses. Stahl issued stock of $9,000 and paid dividends of $15,000 during the year. Stockholders' equity changed by what amount from the beginning of the year to the end of the year?