An existing robot is used in a commercial material laboratory to handle ceramic samples in the high-temperature environment that is part of several test procedures. Due to changing customer needs, the robot will not meet future service requirements unless it is upgraded at a cost of $2500. Because of this situation, a new advanced technology robot has been selected for potential replacement of the existing robot. The accompanying estimates have been developed from information provided by some current users of the new robot and data obtained from the manufacturer. The firms before-tax MARR is 18% per year. Based on this information, should the existing robot be replaced? Assume that a robot will be needed for an indefinite period.

Defender
Current MV	$38,500
Upgrade cost (year 0)	$2,500
Annual expenses	$1,500 in year one, and increasing at the rate of 7% per year thereafter
Useful life (years)	6
Challenger
Purchase Price	$53,000
Installation cost	$5,300
Annual expenses	$800 in year one, and increasing by$200 per year thereafter
Useful life (years)	10
MV at end of useful life	$7,000

The AW value for Defender is $-13612. (Round to the nearest dollar.)

The AW value for Challenger is $-14113. (Round to the nearest dollar.)

The defender should be retained.

Please show me how to get to these answers. Most of my classmates as well as myself cannot figure this out. If able to please show in Excel and show formulas