Answer:
accumulated amortization patent 400,000 dollars
Explanation:
patent original cost: 1,000,000
amortized for 2 years (2015 and 2016) with a useful life of 10 years:
1,000,000 / 10 = 100,000 per year x 2 years = 200,000
1,000,000 - 200,000 = 800,000
Now, as new information is determined we concluce the original useful life was 6 years from acquisition thus, leaving 4 years
800,000 current value / 4 years = 200,000 amortization for 2017
For a total of 200,000 previous + 200,000 for 2017 = 400,000