i dont know how figure out b.) and c.)

Rogers Products uses a periodic inventory system. The company's records show the beginning inventory of PH4 oil fitters on January 1 and the purchases of this item during the current year to be as follows. A physical count indicates 23 units in inventory at year-end. Determine the cost of the ending inventory on the basis of each of the following methods of inventory valuation. (Remember to use petiodic inventory costing procedures.) (Round your intermedinte and final answers to 2 decimal places.)