An existing robot can be kept if $2,000 is spent now to upgrade it for future service

Question:

An existing robot can be kept if $2,000 is spent now to upgrade it for future service requirements. Alternatively, the company can purchase a new robot to replace the old robot. The following estimates have been developed for both the defender and the challenger.
The company's before-tax is 20% per year. Based on this information, should the existing robot be replaced right now? Assume the robot will be needed for an indefinite period of time.
MARR
Minimum Acceptable Rate of Return (MARR), or hurdle rate is the minimum rate of return on a project a manager or company is willing to accept before starting a project, given its risk and the opportunity cost of forgoing other...