How many against have a difference of 6, with a played greater than 19?
CREATE TABLE "laf_s_campeonato_paulista" (
  "position" real,
  "team" text,
  "points" real,
  "played" real,
  "drawn" real,
  "lost" real,
  "against" real,
  "difference" text
);
SELECT SUM("against") FROM "laf_s_campeonato_paulista" WHERE "difference"='6' AND "played">19;