What is the average number of losses when there are more than 4 wins, and the against matches is more than 1728?
CREATE TABLE "1938_ladder" (
  "club" text,
  "wins" real,
  "losses" real,
  "draws" real,
  "against" real
);
SELECT AVG("losses") FROM "1938_ladder" WHERE "wins"<4 AND "against">1728;