gray co. was granted a patent on january 2, year 1, and appropriately capitalized $45,000 of related costs. gray was amortizing the patent over its estimated useful life of fifteen years. during year 4, gray paid $15,000 in legal costs in successfully defending an attempted infringement of the patent. after the legal action was completed, gray sold the patent to the plaintiff for $75,000. gray's policy is to take no amortization in the year of disposal. in its year 4 income statement, what amount should gray report as gain from sale of patent?