Which Frequency has a Website of •, and a Webcast of •in san antonio?
CREATE TABLE "long_range_am_stations" (
  "frequency" real,
  "callsign" text,
  "brand" text,
  "city_of_license" text,
  "website" text,
  "webcast" text
);
SELECT AVG("frequency") FROM "long_range_am_stations" WHERE "website"='•' AND "webcast"='•' AND "city_of_license"='san antonio';