I can't figure out this last part! Please explain.

Lean Accounting Speaker assembly cell, estimated costs: Labor Depreciation Supplies Power Total cell costs for the period $26,750 3,590 1,310 975 $32,625 1. Purchased materials to produce 450 speaker units. 2. Applied conversion costs to production of 430 speaker units. 3. Completed and transferred 410 speaker units to finished goods. 4. Sold 390 speaker units. There were no inventories at the beginning of the period. 1. Raw and In Process Inventory Accounts Payable 2. Raw and In Process Inventory Conversion Costs 3. Finished Goods Inventory Raw and In Process Inventory