A critical machine in BHP Billiton's copper refining operation was purchased 7 years ago for $160,000. Last year a replacement study was performed with the decision to retain it for 3 more years. The situation has changed. The equipment is estimated to have a value of $8000 if "scavenged" for parts now or anytime in the future. If kept in service, it can be minimally upgraded at a cost of $43,000 to make it usable for up to 2 more years. Its operating cost is estimated at $22,000 in the first year and $29,000 in the second year. Alternatively, the company can purchase a new system, the challenger, that will have an AW_C of $53,500 over its ESL. Use a MARR of 10% per year and annual worth analysis to determine when the company should replace the machine.

The AW value of the challenger is $

and the AW value of the defender at the end of year 2 is $ .

The company should replace the machine (after 2 yrs) or (Now)