$2.$ A new instrument is purchased for the control laboratory 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 straight$-$line depreciation after $5$ yr$.$