Answer:
Amortization expense for the year 2018: 31,875
Explanation:
The copyright will need to adjust the amortization base on the new information.
150,000 / 20 = 7,500 amortization per year
Depreciation from 2015 to 2017 : 3 x 7,500 = 22,500
book value at Jan 1st, 2018 = 150,000 - 22,500 = 127,500
From there we are given new information about the economic life.
We did not have knowledge before, so we don't adjust prior periods.
We recalculate the amortization:
economif life from Jan 2018 to Dec 2021 = 4 years
127,500 / 4 years = 31,875 per year
Amortization expense for the year 2018: 31,875