what Area has the frequency of 100.3 and an On-air ID of yass fm?
CREATE TABLE "defunct_callsigns" (
  "callsign" text,
  "area_served" text,
  "frequency" text,
  "band" text,
  "on_air_id" text,
  "purpose" text
);
SELECT "area_served" FROM "defunct_callsigns" WHERE "frequency"='100.3' AND "on_air_id"='yass fm';