$($a$)$ Calculate the cost of the ending inventory and the cost of goods sold for each cost flow assumption, using a perpetual inventory

system. Assume a sale of $690$ units occurred on June $15$ for a selling price of $$8$ and a sale of $720$ units on June $27$ for $$9.($Round

average cost per unit to $3$ decimal places, e$.$g$.5\mathrm{.}254$ and final answers to $0$ decimal places, e$.$g$.2,520.)$