Comparing three depreciation methods

Dexter Industries purchased packaging equipment on January $8$ for $$81,900.$ The equipment was expected to have a useful life of $3$ years, or $20,000$ operating hours, and a residual value of $$4,500.$ The equipment was used for $7,600$ hours during Year $1,6,000$ hours in Year $2,$ and $6,400$ hours in Year $3.$

Required:

$1.$Determine the amount of depreciation expense for the $3$ years ending December $31,$ by $($a$)$ the straight$-$line method, $($b$)$ the units$-$of$-$activity method, and $($c$)$ the double$-$declining$-$balance method. Also determine the total depreciation expense for the $3$ years by each method. Do not round intermediate calculations when determining the depreciation rate. Round the final answers for each year to the nearest whole dollar.