What is the average final with an all around larger than 19.4 and total more than 39.9?
CREATE TABLE "finals_6_balls" (
  "place" real,
  "nation" text,
  "all_around" real,
  "final" real,
  "total" real
);
SELECT AVG("final") FROM "finals_6_balls" WHERE "all_around">19.4 AND "total">39.9;