What is the average value for Lost, when the value for Goals Scored is greater than 20, and when the value for Played is less than 18?
CREATE TABLE "clausura_2004_standings" (
  "place" real,
  "team" text,
  "played" real,
  "draw" real,
  "lost" real,
  "goals_scored" real,
  "goals_conceded" real,
  "points" real
);
SELECT AVG("lost") FROM "clausura_2004_standings" WHERE "goals_scored">20 AND "played"<18;