CREATE TABLE "round_6" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: Which Crowd has an Away team score of 9.21 (75)?
SQL: SELECT SUM("crowd") FROM "round_6" WHERE "away_team_score"='9.21 (75)';