please explain and show work thank you.

30. Lightening Company's record of transactions concerning light bulbs for the month of April was as follows. Purchases Sales April 1 units 500 400 Unit Cost $ 3 $ 4 units April 5 300 12 200 Selling Price $10 $10 11 300 $ 4.5 Compute the ending inventory on April 30 using perpetual average-cost assumption (Show work in case of rounding errors) $1792.59