Explanation, please.

Question 16 0/5 pts Dali's Timepieces had the following inventory data: Date Quantity Unit Cost July 1 Beginning inventory 5 $49 July 4 Purchase 10 $57 July 7 Sale 12 July 11 Purchase 9 $54 July 14 Sale 8 Assuming average cost, what is the cost of goods sold for the July 7 sale? (Round any intermediary calculations to the nearest cent and round your final answer to the nearest dollar.) Correct Answer $652 You Answered $668 $636 $644