Please help me! When I did it on paper, my answer is totally different from the answers they gave.

Date Salmone Company reported the following purchases and sales of its only product. Salmone uses a perpetual inventory system. Determine the cost assigned to the ending inventory using FIFO. Activities Units Acquired at Cost Units Sold at Retail May 1 Beginning Inventory 150 units @ $10.00 5 Purchase 220 units @ $12.00 10 Sales 140 units @ $20.00 15 Purchase 100 units @ $13.00 24 Sales 90 units @ $21.00 $2,850 $2.980 $2,590 $2,860 $2,460 Ooooo