9. A During the design of a new industrial building, two lighting systems are being considered with the costs as listed below. Mercury Vapor Lighting Fluorescent Lighting Cost New $24,000 $45,000 Annual Operating Cost $14,000/year $12,500/year Salvage Value $3,000 $6,000 Expected Life 20 years 40 years Use incremental rate of return (IROR) method for comparing alternatives and a MARR of 9% per year a) What is the incremental Rate of Return? b) Which lighting systems should you choose