Wilders outfitters and adventures clothes merchandiser began the month with 100 parkas in inventoty. During the month the store purchased 300 more parkas from its suppliers. A count at the end of the month found that 70 parkas remained on hand how many parkas did ?

Your question got cut off, but it sounds like you are learning about cost of goods sold. Think of it this way (this is in units, not dollars, but the same idea):

Beginning Inventory + Purchases = Available for sale

Available for sale - Sold = Ending inventory

-or-

Available for sale - Ending inventory = Sold