What is the average area of the city that has a density less than than 206.2 and an altitude of less than 85?
CREATE TABLE "communes" (
  "rank" text,
  "city" text,
  "population" real,
  "area_km_2" real,
  "density_inhabitants_km_2" real,
  "altitude_mslm" real
);
SELECT AVG("area_km_2") FROM "communes" WHERE "density_inhabitants_km_2"<206.2 AND "altitude_mslm"<85;