Aerotron Electronics is considering purchasing a water filtration system to assist in circuit board manufacturing. The system costs $40,000. It has an expected life of 7 years at which time its salvage value will be $7,500. Operating and maintenance expenses are estimated at $2,000 per year. If the filtration system is not purchased, Aerotron Electronics will have to pay Bay City $12,000 per year for water purification. If the system is purchased, no water purification from Bay City will be needed. Aerotron Electronics' MARR is 10% compounded annually. What is the present worth of this investment?