Sundance Detective Agency purchased new surveillance equipment with the following estimates. Note: The year index is n = 1, 2, 3, ... to calculate the maintenance costs and extra revenues for the corresponding years. First cost ($) 1,050 Annual maintenance cost ($ in year n) 70 + 5n Extra revenue ($ in year n) 200 + 50n Salvage value ($ at the end of the useful life) 600