Machinery purchased for $66,000 by Metlock Co. in 2016 was originally estimated to have a life of 8 years with a salvage value of $4,400 at the end of that time. Depreciation has been entered for 5 years on this basis. In 2021, it is determined that the total estimated life should be 10 years with a salvage value of $4,950 at the end of that time. Assume straight-line depreciation.

a.)Prepare the entry to correct the prior years' depreciation, if necessary. (If no entry is required, select "No entry" for the account titles and enter 0 for the amounts. Credit account titles are automatically indented when amount is entered. Do not indent manually.)

b.)Prepare the entry to record depreciation for 2021. (If no entry is required, select "No entry" for the account titles and enter 0 for the amounts. Credit account titles are automatically indented when amount is entered. Do not indent manually. Use Machinery related account.)