What is the Height of the Canterbury House with 12 Floors and a Rank of 75=?
CREATE TABLE "tallest_completed_buildings_and_structur" (
  "rank" text,
  "name" text,
  "height_m" real,
  "height_ft" real,
  "floors" text
);
SELECT AVG("height_ft") FROM "tallest_completed_buildings_and_structur" WHERE "floors"='12' AND "rank"='75=' AND "name"='canterbury house';