Digger Inc., an oil production company, purchased a machine on April 1, 2021.

The following information applies:

Cost	Estimated useful life	Residual value
$40,000	4 years	$10,000
	(100,000 tonnes)

The machine has an estimated useful life in production output of 100,000 tonnes. Actual output was: 2021 40,000 tonnes; 2022 20,000 tonnes; 2023 10,000 tonnes. The year-end of the company is December 31. Assume the company uses the year rule to calculate depreciation expense in the year of acquisition and disposal.

Required:

Calculate the depreciation expense at each year-end for 2021 and 2022 under each of these depreciation methods: straight-line and usage. (6 marks)