Chapter 20 question 2I'm confused by this?

Irwin, Inc. constructed a machine at a total cost of $58 million. Construction was completed at the end of 2017 and the machine was placed in service at the beginning of 2018. The machine was being depreciated over a 10-year life using the sum-of-the-years'-digits method. The residual value is expected to be $3 million. At the beginning of 2021, Irwin decided to change to the straight-line method. Ignoring income taxes, prepare the journal entry relating to the machine for 2021. (If no entry is required for a transaction/event, select "No journal entry required" in the first account field. Do not round intermediate calculations. Enter your answers in millions rounded to 1 decimal place (i.e., 5,500,000 should be entered as 5.5).) View transaction list Journal entry worksheet V Record the entry relating to the machine for 2021.