Martinez Furniture Ltd. uses a perpetual inventory system and has a beginning inventory, as at June 1, of 490 bookcases at a cost of $126 each. During June, the company had the following purchases and sales of bookcases: Purchases Sales Date Units Unit cost Units Unit price June 6 1,210 $128 10 1,050 $206 14 1,850 129 16 1,520 211 26 1,020 130 (a)