Zephyr Minerals completed the following transactions involving machinery. Machine No. 1550 was purchased for cash on April 1, 2017, at an installed cost of $58,000. Its useful life was estimated to be six years with a $4,000 trade-in value. Straight-line depreciation was recorded for the machine at the ends of 2017, 2018, and 2019. On March 29, 2020, it was traded for Machine No. 1795, with an installed cash price of $66,000. A trade-in allowance of $30,610 was received for Machine No. 1550, and the balance was paid in cash. The fair values of Machine No. 1550 and Machine No. 1795 could not be determined. Machine No. 1795s life was predicted to be four years with a trade-in value of $8,600. Double declining-balance depreciation on this machine was recorded each December 31. On October 2, 2021, it was traded for Machine No. BT-311, which had an installed cash price of $487,000, the machines fair value. A trade-in allowance of $10,000 was received for Machine No. 1795, and the balance was paid in cash. It was estimated that Machine No. BT-311 would produce 200,000 units of product during its five year useful life, after which it would have a $15,000 trade-in value. Units-of-production depreciation was recorded for the machine for 2021, a period in which it produced 28,000 units of product. Between January 1, 2022, and August 21, 2024, the machine produced 103,000 more units. On August 21, 2024, it was sold for $81,600. Required: Prepare journal entries to record: (Round intermediate calculations to the nearest whole dollar.) a. The depreciation expense recorded to the nearest whole month on the first December 31 of each machines life. (Round the final answers to the nearest whole dollar. If no entry is required for a transaction, select "No journal entry required" in the first account field.)

b. The purchase/exchange/disposal of each machine. (Round the final answers to the nearest whole dollar. If no entry is required for a transaction, select "No journal entry required" in the first account field.)