The floor area ratio provisions of Section 24-11 (Maximum Floor Area Ratio and Percentage of Lot Coverage), inclusive, shall be modified for certain areas as follows:

(a)        in R8B Districts within Community District 8, in the Borough of Manhattan, the maximum floor area ratio on a zoning lot containing community facility uses exclusively shall be 5.10;

(b)        in R10 Districts, except R10A or R10X Districts, within Community District 7, in the Borough of Manhattan, all zoning lots shall be limited to a maximum floor area ratio of 10.0; and

(c)        in R9 and R10 Districts, for zoning lots containing a building that is developed or enlarged pursuant to the applicable tower regulations of Section 23-65 (Tower Regulations), inclusive, the provisions of paragraph (a)(2) of Section 23-16 (Special Floor Area and Lot Coverage Provisions for Certain Areas) shall apply:

(1)        to only the residential portion of a building where less than 75 percent of the total floor area of such building is allocated to residential use; and

(2)        to the entire building where 75 percent or more of the total floor area of such building is allocated to residential use.