$7-5.$ A new scanning device has an installed cost basis of $$28,000$ and an estimated service life of eight years. It will have a zero salvage value at that time. The $200\%$ declining balance method is used to depreciate this asset. $(7\mathrm{.}3)$

a$.$ What will the depreciation charge be in year eight?

b$.$ What is the book value at the end of year seven?

c$.$ What is the gain $($or loss$)$ on the disposal of the device if it is sold for $$1,000$ after seven years?