Use the following to answer questions 18 - 19 AD Enterprises purchased equipment for $400,000 on January 1, year 1. The equipment is expected to have a 4- year life, with a residual value of $50,000 at the end of its service life. 18. $ Using the double-declining balance method, determine depreciation expense for year 2. 19. $ Using the straight-line method, determine book value at the end of year 2.