Answer:
LIFO method
2019 = $98000 (Sam's as before)
2020
Inventory at 2020 without indexation = $117502/1.1
= $106820
Increase in inventory = $106820 - $98000 = $8820
Inventory according to LIFO
= Last year inventory + (addition indexed amount)
= $98000 + ($8820*1.1)
= $107702
2021
Inventory of 2021 2020 price
= $131400/1.2
= $109500
Change in inventory = $109500 - $106820
= $2680
Inventory at 2021 according to LIFO
= $98000 + ($8820*1.10) + ($2680*1.20)
= $110918