Please explain

The following information applies to the questions displayed below. For the current year, Parker Games has the following inventory transactions related to its traditional board games. Parker Games uses a periodic inventory system. Transaction Units Cost Total Cost Date Jan. 1 Mar. 12 Sep. 17 Beginning inventory 114 $%21 $ 2,394 1.392 513 Purchase Purchase 87 57 16 9 258 4,299 Jan. 1-Dec. 31 Sales 167 Because of the increasing popularity of electronic video games, Parker Games continues to see a decline in the demand for board games. Sales prices have decreased by over 50% during the year. At the end of the year, Parker estimates the net realizable value the 91 units of unsold inventory is only $470