$12\mathrm{.}4$ A real$-$estate developer seeks to determine the most economical height for a new office building, which will be sold after five years. The relevant net annual revenues and salvage values on after$-$tax basis are as given in Table P$12\mathrm{.}4.$

Table P$12\mathrm{.}4$

$\backslash$table$[[,$Height$],[,2$ Floors,$3$ Floors,$4$ Floors,$5$ Floors$],[$First cost$,$$$500,000,$$$750,000,$$$1,250,000,$$$2,000,000$