The questions is about chapter 9 (Reporting and Analyzing Long Lived Assets) of accounting by Paul Kimmel. Please I need detail explanation of how you know the months eg I see the table (64000-3000)/5x3 the 5 stands for the 5years given in the statement but the month (ie the 3) I don't where it is coming from. this the question

Sunland Company owns equipment that cost $73,000 when purchased on January 1, 2019. It has been depreciated using the straight-line method based on an estimated salvage value of $13,000 and an estimated useful life of 5 years. Prepare Sunland Companys journal entries to record the sale of the equipment in these four independent situations. (Credit account titles are automatically indented when amount is entered. Do not indent manually. If no entry is required, select "No Entry" for the account titles and enter 0 for the amounts.)

(a)		Sold for $39,000 on January 1, 2022.
(b)		Sold for $39,000 on May 1, 2022.
(c)		Sold for $22,000 on January 1, 2022.
(d)		Sold for $22,000 on October 1, 2022.