Which sum of week that had an attendance larger than 55,767 on September 28, 1986?
CREATE TABLE "schedule" (
  "week" real,
  "date" text,
  "opponent" text,
  "result" text,
  "attendance" real
);
SELECT SUM("week") FROM "schedule" WHERE "attendance">'55,767' AND "date"='september 28, 1986';