Depreciation for the asset is calculated when it was purchase and not for the calendar year. And it’s not depreciated in the year it is expected to sold
Joseph: If it is proportional in the year of purchase and year of sale then you depreciate depending on how many months it was owned in each year. (The alternative is when questions tell you that there is a full years charge in the year of purchase and none in the year of sale)
I do suggest that you watch the free lectures on depreciation where both alternatives are explained.