20 10 to 20 15, the amortization amount should be135,000 yuan, so the book value at the end of 2018000-135,000 yuan = 45,000 yuan.
At the end of 20 15, the recoverable amount is 25,000 yuan (lower than its book value of 45,000 yuan, indicating impairment), and the provision for impairment is 20,000 yuan.
Amortization amount of 20 16 years = 20 16 book value at the beginning of the year/useful life = 25,000/2 =12,500 (yuan)