How is an impairment loss on property plant and equipment determined and measure

How is an impairment loss on property plant and equipment determined and measured under IFRS? How does this differ from US GAAP?
Please determine the amount at which the inventory should be reported on December 31 Year 1 balance sheet using the following information:
Historical cost$20000Replacement cost$14000Estimated selling price$17000Estimated costs to complete and sell$2000Normal profit margin as a percentage of selling price20%
The entire inventory on hand at December 31 Year 1 was completed in Year 2 at a cost of $1800 and sold at a price of $17150.Determine the impact on income in Year 1 and Year 2 under (1) IFRS and (2) US GAAP.