Q$\mathrm{.}5$ A coal$-$fired power plant has upgraded an emission control valve. The modification costs only $$8000$ and is expected to last $6$ years with a $$200$ salvage value. The maintenance cost is expected to be high at $$1700$ the first year, increasing by $11\%$ per year thereafter. Determine the equivalent present worth of the modification and maintenance cost at $15\%$ per year.