How to get 40 unit!?

Date Specific Identification COST of GOODS AVAILABLE FOR SALES COST of GOODS SOLD ENDING INVENTORY # of units cost per unit(S) cost of goods(S)# of units Cost per units(s) # of units cost per unit(S) Ending Inventory(S) January 1 Beginning inventory 140 6 840 January 10 Goods Sold 100 6 600 40 6 240 January 20 Purchase(60 units @$5-$300) 100 5, 4 540 January 20 40+60 =100 540/100=54 240+300 = 540 100 5, 4 540 January 25 Goods Sold 100 5, 4 540 80 5, 4 432(5, 4*80) 20 5, 4 (5, 4*20)108 January 30 Purchased (180 units@$4.5-$810) January 30 180+20 =200 918/200=4.59 (108+810=918) 200 4.59 918 COST OF INVENTORY (ESTATES CONTENT) Description Cost(S) Purchase Price 38, 500 Transportation 1, 700 Insurance 250 Refurbish cost 590 TOTAL COST OF INVENTORY 41, 040