During 2020, Starnes Corporation developed a patent. Starnes incurred the following costs related to the development of the patent: tests to perfect the use of the patent for production processes, $6,000; research costs in the research laboratory, $21,000; and depreciation on equipment (that has alternative future uses) used in developing the patent, $4,000. In addition, in late December 2020, the company incurred legal fees for the patent registration, $7,000. The expected life of the patent is 20 years. On September 30, 2021, Starnes Corporation defended its patent in court after incurring legal fees of $3,000. The total estimated life of the patent at that time was adjusted to 15 years remaining from September 30, 2021.

Record journal entries for the following items.

Note: Round your final answers to the nearest whole dollar.

Note: List debits and credits in alphabetical order based upon the account name.

a. Patent development and registration costs incurred in 2020.

b. Legal fees paid in 2021.

c. Amortization expense in 2021.

d. Amortization expense in 2022c. Amortization expense in 2021.