Maritime Audio Limited has 10 home audio systems on hand at January 1, which cost $325 each at the time of purchase. Maritime purchased 20 systems during the year for a total cost of $7,000. During the year, 25 systems were sold at a selling price of $579 each. According to the company's perpetual inventory system, the company had sold all of the systems that were on hand at the beginning of the year and 15 of the systems purchased during the year.

1. Determine the following amounts in both units and dollars:
2. Beginning inventory on January 1
3. Cost of goods purchased during the year
4. Cost of goods available for sale for the year
5. Cost of goods sold for the year
6. Ending inventory on December 31

How to comprehend 5 and 6. I don't get how to do it