A small company spends $8000 per year on heating. The costs of natural gas for heating are expected to rise a 10% per year at one year from now (EOY 1). The maintenance on the gas furnace is $345 per year and this is expected to increase by 15% per year starting one year from now. If the planning horizon is 15 years, what is the equivalent annual expernse for operating and maintaining the furnace? i = 18%