Gordon Company bought a copyright for $90,000 on January 1, 2012, at which time the copyright had an estimated useful life of 15 years. On January 5, 2015, the company determined that the copyright would expire at the end of 2016.

How much should Gordon record as amortization expense for this copyright for 2015?

How much should Gordon record retrospectively as the effect of change?

Please provide explanation, thank you.