In the RMD, RHD and RSD Districts, for each on-site affordable unit, the applicant may propose two additional dwelling units over the number of units that would otherwise be permitted in the district. The minimum lot area shall be not less than 85% of the minimum lot area for a detached one-family dwelling, nor less than 80% of the minimum lot area per unit for a two-family or semidetached dwelling, nor less than 70% of the minimum lot area per unit for a multifamily unit, as set forth in Subsection D of §§ 300-36 through 300-38, as applicable.