How to record this transaction and what is its impact on the financial statements?

Q-The corporation decided to change its method of inventory pricing from average cost to the FIFO method. The effect of this change on prior years is to increase 2016 income by $ 60,000 and decrease 2017 income by $ 20,000 before taxes. The FIFO method has been used for 2018. The tax rate on these items is 40%.