An asset for a production line was purchased and placed in service by a large manufacturing company. It costs $55000 with a trade in of the old unit which is valued at $5000. The new asset has an estimated salvage value of $4000 at the end of an estimated useful life of 8 years. If the 150% DB with a switchover to SL method is used for the depreciation, a) from which year would the switchover happen? b) what is the depreciation value in year 7