An elevator system in an office building can either be refurbished or replaced. Refurbishing the elevators will cost $$55,000$ and extend the life of the elevators another $20$ years. Salvage value at the end of $20$ years will be $$11,000.$ Annual maintenance costs will be $$1,000$ per year. The current salvage value of the elevators is $32,000.$ If interest rate is $4\%,$ the annual equivalent cost for refurbish the elevators is $4,680$ $$3,7505,9307,0308,240$