A small company heats its building and will spend $9,592 in year 1 on natural gas for this purpose. Cost increases of natural gas are expected to be 9% per year starting year 2. Their maintenance on the gas furnace is going to be $386.40 in the first year and this expense is expected to increase by 12% per year starting year 2. If the planning horizon is 13 years, what is the total annual equivalent expense for operating and maintaining the furnace? The interest rate is 18% per year. (a) The total present worth of operating and maintaining the furnace is $ 72248. (Round to nearest dollar) (b) The total annual equivalent expense for operating and maintaining the furnace is $14714. (Round to nearest dollar)