Hemming Company reported the following current$-$year purchases and sales for its only product.

Hemming uses a periodic inventory system. Ending inventory consists of $40$ units from the March $14$ purchase, $80$ units from the July

$30$ purchase, and all $190$ units from the October $26$ purchase. Using the specific identification method, calculate the following.

a$)$ Cost of Goods Sold using Specific Identification

b$)$ Gross Margin using Specific Identification