The Planning Board may by special permit award a density bonus for a development that includes more than the minimum number of affordable units required under § 173-205 provided that all of affordable units will be located within the development. For each additional affordable unit over and above the minimum, the Board may approve three additional market-rate units, up to a maximum density bonus of 75%. Example: for a development of 12 housing units, compliance with this Article XXIX would require two affordable units. The applicant who agrees to provide two more affordable units on site (12 + 2 = 14) may request an additional six market-rate units (three per additional affordable unit), bringing the total development to 20 units.