On the date of 30/01/1991, when the away team was Liverpool, what was the score?
CREATE TABLE "fourth_round_proper" (
  "tie_no" text,
  "home_team" text,
  "score" text,
  "away_team" text,
  "date" text
);
SELECT "score" FROM "fourth_round_proper" WHERE "date"='30/01/1991' AND "away_team"='liverpool';