You are designing a new home and have to decide between two insulated roofing systems. One made of steel and the other plastic. The steel one will last longer, but costs more up front. Based on the information the manufacturers have provided you come up with the following estimates. Steel System Plastic System Service Life 21 years 14 Years First Cost S 22,500 5 15,030 Heat savings 5 3,100 / year S 2,500 [year Maintenance costs S 30 / year 5 120 I year Salvage Value (After service life) $2,200 Nil Disposal Cost {After service life) $1,000 $1,000 If the interest rate is 10% which system should you purchase