Grove Company acquired a production machine on January $1,2022,$ at a cost of $$490,000.$ The machine is expected to have a four$-$year useful life, with a salvage value of $$84,000.$ The machine is capable of producing $54,000$ units of product in its lifetime. Actual production was as follows: $11,880$ units in $2022$; $17,280$ units in $2023$; $15,120$ units in $2024$; $9,720$ units in $2025.$

Following is the comparative balance sheet presentation of the net book value of the production machine at December $31$ for each year of the asset$$s life, using three alternative depreciation methods $($items a to c$)$:

Required:

Identify the depreciation method used for each of the following comparative balance sheet presentations $($items a to c$).$ If a declining$-$balance method is used, be sure to indicate the percentage $(150\%$ or $200\%).($Hint: Read the balance sheet from right to left to determine how much has been depreciated each year. Remember that December $31,2022,$ is the end of the first year.$)\backslash$table$[[$Production Machine, Net of Accumulated Depreciation$],[,$Depreciation Method,,At December $31],[,,2025,2024,2023,2022],[$a$.,$Units of production method,$ox,84,000,185,500,287,000,388,500],[$b$.,$Double$-$declining$-$balance $(200\%)$ method,$ox,84,000,157,080,270,760,400,680],[$c$.,$Straight$-$line method,$ox,84,000,84,000,122,500,245,000]]$