What is the to par of the player from the United States with a t6 place and a score of 70-73-68-73=284?
CREATE TABLE "final_round" (
  "place" text,
  "player" text,
  "country" text,
  "score" text,
  "to_par" text,
  "money" real
);
SELECT "to_par" FROM "final_round" WHERE "country"='united states' AND "place"='t6' AND "score"='70-73-68-73=284';