What is the to par of the player from the United States with a place of t1 and a 76-68=144 score?
CREATE TABLE "second_round" (
  "place" text,
  "player" text,
  "country" text,
  "score" text,
  "to_par" text
);
SELECT "to_par" FROM "second_round" WHERE "country"='united states' AND "place"='t1' AND "score"='76-68=144';