What were the lowest goals when there were mor than 15 wins and the goal difference was larger than 35?
CREATE TABLE "relegation_playoff" (
  "position" real,
  "club" text,
  "played" real,
  "points" real,
  "wins" real,
  "draws" real,
  "losses" real,
  "goals_for" real,
  "goals_against" real,
  "goal_difference" real
);
SELECT MIN("goals_for") FROM "relegation_playoff" WHERE "wins">15 AND "goal_difference">35;