I need help with calculating Amortization expense for the patent. Can you please explain how you got the answer and answer my question below?

I'm stuck on getting the amortization expense for 2019 because I can't figure out how many years of the useful life I should use for that calculation (do you need to subtract the 2016, 2017, and 2018 years from the original 10 years useful life?)

Thank you!

QUESTION 9 On January 1, 2016, Red Inc. purchased a patent for $23,800. In addition to the purchase price, Red paid legal fees of $1,200 to obtain the patent. Red believes this patent will help to increase its sales for the next 10 years, however; the legal remaining life on the patent is 14 years. On January 1, 2019, Blue was sued for patent infringement and had to spend $3.500 in legal fees to successfully defend the patent. Determine the book value on this patent at the end of both 2018 and 2019. 2018 2019 A. $2,500 $2,500 B. $25,000 $28,500 C.$17,500 $18,000 D. $17,500 $15,000 E. $21,000 $18,000