Please help using LIFO METHOD!!

Perpetual inventory using LiFO Beginning inventory, purchases, and sales data for prepaid cell phones for December are as follows: Inventory Dec. 1310 units at $88 Sales Dec, 12.240 units 14.166 units 31200 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 Hllustrated 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. 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