A homeowner is considering an upgrade of a fuel oil-based furnace to a natural gas unit. The investment in the fixed equipment, such as a new boiler, will be $2500 installed. The cost of the natural gas will average $60 per month over the year instead of the $145 per month that the fuel oil costs. If funds cost 9% per year and differential inflation in fossil fuels will be 3% per year, how long will it take to recover the initial investment? (Solve on a monthly basis.)