Zimmer Company owns an executive plane that originally cost $$2,816,000.$ It has recorded straight$$line depreciation on the plane for seven full years, calculated assuming a $$352,000$ expected salvage value at the end of its estimated $10$year useful life. Zimmer disposes of the plane at the end of the seventh year.

a$.$ At the disposal date, what is the $(1)$ cumulative depreciation expense and $(2)$ net book value of the plane?

$(1)$ Cumulative depreciation expense :

$(2)$ Net book value: