What's the total attendance for H/A of A and opponents of wolverhampton wanderers?
CREATE TABLE "pre_season_and_friendlies" (
  "date" text,
  "opponents" text,
  "h_a" text,
  "result_f_a" text,
  "attendance" real
);
SELECT COUNT("attendance") FROM "pre_season_and_friendlies" WHERE "h_a"='a' AND "opponents"='wolverhampton wanderers';