Weeping Willow Co. is a greeting card wholesaler. Below is the inventory information for the month of December # of units Cost per unit 12/1/2021 Beginning inventory 100 $14 12/13/2021 Sale 40 12/17/2021 Purchase 200 $15 12/20/2021 Sale 230 Each unit of greeting cards sell for $20. What is Weeping Willow's ending inventory for December assuming a periodic LIFO inventory cost system? O $900 O $450 $840 O $420