Beginning inventory, purchases, and sales data for prepaid cell phones for December are as follows:

Inventory

Dec. $11,800$ units at $$36$

Purchases

Dec. $10900$ units at $$38$

$20810$ units at $$40$

Sales

Dec. $121,260$ units

$141,080$ units

$31540$ units

a$.$ Assuming that the perpetual inventory system is used, costing by the LIFO method, determine the cost of goods sold for each sale

and the inventory balance after each sale, presenting the data in the form illustrated in Exhibit $4.$ Under LIFO, if units are in inventory at

two different costs, enter the units with the HIGHER unit cost first in the Cost of Goods Sold Unit Cost column and LOWER unit cost first

in the Inventory Unit Cost column.