A large city in the mid-West needs to acquire a street-cleaning machine to keep its roads looking

Question:

A large city in the mid-West needs to acquire a street-cleaning machine to keep its roads looking nice year round. A used cleaning vehicle will cost $75,000 and have a $20,000 market (salvage) value at the end of its five-year life. A new system with advanced features will cost $150,000 and have a $50,000 market value at the end of its five-year life. The new system is expected to reduce labor hours compared with the used system. Current street-cleaning activity requires the used system to operate 8 hours per day for 20 days per month. Labor costs $40 per hour (including fringe benefits), and is 12% per year compounded monthly.
a. Find the breakeven percent reduction in labor hours for the new system.
b. If the new system is expected to be able to reduce labor hours by 20% compared with the used system, which machine should the city purchase?
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...