The answer is c but could someone explain why and work the problem for me to see?

3. Benedict Company compiled the following financial information as of December 31, 2017 Service revenue Common stock Property Operating expenses Cash Dividends Equipment Accounts payable Accounts receivable Retained earnings, 1/1/17 Benedict's retained earnings on December 31, 2017 are a. $600,000 b. $720,000 c. $640,000 d. 40,000 $1,120,000 240,000 320,000 1,000,000 280,000 80,000 40,000 160,000 120,000 600,000