A new instrument is purchased for the control taboratory of a plant at a cost of $$200,000.$ It is estimated to have a $10-yr$ useful life with a salvage value of $$30,000.$ Estimate the amount of depreciation each year by the following methods:

a$.$ Straight$-$line depreciation over $10$ yr based on $$200000$$$30000=$$$170000.$

b$.$ Declining$-$balance depreciation with $d=1-n.$

c$.150\%$ declining$-$balance depreciation.

d$.$ Double declining$-$balance depreciation.

e$.$ Combination method of double declining$-$balance depreciation switching to straightline depreciation after $5yr.$