i have the answer just dont know how to work it out.

Selected financial information for Red and Black Corp. is presented in the following table (000s omitted). Sales revenue $4200 Purchases of direct materials $480 Direct labor $500 Manufacturing overhead $700 Operating expenses $680 Beginning raw materials inventory $290 Ending raw materials inventory $200 Beginning work in process inventory $410 Ending work in process inventory $460 Beginning finished goods inventory $340 Ending finished goods inventory $300 What was cost of goods sold? Selected Answer: $1680 Answers $1680 $1760 $1790 $960