Table Fresh Foods purchased a machine to package its presliced garden salads. The

machine costs $$20,100$ and has an estimated life of $30,000$ hours and a salvage value of

$$1500.$ Use the units$-$of$-$production method of depreciation to find $($a$)$ the annual amount

of depreciation and $($b$)$ the book value at the end of each year, given the following use

information: year $1$: $7800$ hours; year $2$: $4300$ hours; year $3$: $4850$ hours; year $4$: $7600$

hours.