IE department is thinking of replacing the current workstation ZM-640 in the lab due to performance problems. ZM-640 was purchased 8 years ago and originally cost 28000 TL. It has a present realizable MV of 22000 TL. A new workstation will require an investment of 34000 TL and is expected to have year end market values(MV) and annual expenses (AE) as follows :

ZM-640	End of Year k	MV, End of Year k (TL)	Annual Expenses, Ek (TL)
	1	17000	5000
	2	14000	7000
	3	9000	7000
	4	6000	4000

New workstation	End of Year k	MV, End of Year k (TL)	Annual Expenses, Ek (TL)
	1	26000	3000
	2	19000	4000
	3	16000	4000
	4	8000	2000

a) Fill the tables below using a before-tax MARR value of 10% per year.

Challenger	TCk	EUACk
End of Year k
1
2
3
4

Defender	TCk	EUACk
End of Year k
1
2
3
4

b) For how many years should the new workstation be retained in service if purchased?

c) Due to budget constraint, keeping ZM-640 is also an option. What is the economic life of the current asset?

d) At the end of which year should the defender be replaced?

(PLEASE, ANSWER BY EXPLAINING. I want to learn that how you solve it.)