For the game on 13 December 1975 with Halifax Town as the away team what was the score?
CREATE TABLE "second_round_proper" (
  "tie_no" text,
  "home_team" text,
  "score" text,
  "away_team" text,
  "date" text
);
SELECT "score" FROM "second_round_proper" WHERE "date"='13 december 1975' AND "away_team"='halifax town';