Perpetual inventory using FIFO

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

Inventory

Dec. $1310$ units at $$88$

Purchases

Dec. $10144$ units at $$90$

$20240$ units at $$96$

Sales

Dec. $12240$ units

$14166$ units

$31200$ units

first in the Cost of Goods Sold Unit Cost column and in the Inventory Unit Cost column.