A small company heats its building using a gas furnace. It expects to spend

​$8 comma 8008,800

on natural gas this first year. The cost of the natural gas is expected to increase by

1010​%

per year every subsequent year. There is also the maintenance cost on the gas furnace which is expected to be

​$874.00874.00

in the first year and to increase by

1515​%

per year every subsequent year. The planning horizon is

1515

years and the company uses an annual interest rate of

1818​%

for economic analysis of its investments.

(a) The projected annual cost of natural gas in year

15 need calculations only