What is the average Rebounds, when Minutes Played is "113", and when Games Played is greater than "18"?
CREATE TABLE "player_stats" (
  "player" text,
  "games_played" real,
  "minutes_played" real,
  "minutes_played_per_game" real,
  "rebounds" real,
  "rebounds_per_game" real,
  "assists" real,
  "assists_per_game" real,
  "field_goal_pct" real,
  "free_throw_pct" real,
  "points" real,
  "points_per_game" real
);
SELECT AVG("rebounds") FROM "player_stats" WHERE "minutes_played"=113 AND "games_played">18;