What is the smallest number of "goals for" out of the clubs where there were 18 wins and fewer than 38 "goals against"?
CREATE TABLE "final_table" (
  "position" real,
  "club" text,
  "played" real,
  "points" text,
  "wins" real,
  "draws" real,
  "losses" real,
  "goals_for" real,
  "goals_against" real,
  "goal_difference" real
);
SELECT MIN("goals_for") FROM "final_table" WHERE "wins"=18 AND "goals_against"<38;