What is the meaning of the following terms: (a) physical inventory; (b) book inventory?

Beginning inventory Purchases and sales data for commodity d45 are as follows:

Jan. 1. Inventory............................................. 15 units at $40

5. Sold ....................................................... 5 units

10. Purchased............................................ 10 units at $41

17. Sold........................................................ 12 units

22. Sold......................................................... 3 units

30. Purchased............................................... 10 units at $42

The enterprise maintains a perpetual inventory system, costing by the first -in, first-out method. Determine the cost of the merchandise sold in each sale and inventory balance after each sale, presenting the data.