What is the area of Cromwell Primary school, which has a state authority?
CREATE TABLE "central_otago_district" (
  "name" text,
  "years" text,
  "gender" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT "area" FROM "central_otago_district" WHERE "authority"='state' AND "name"='cromwell primary school';