How many opponents were there for the game recorded as 6-4 in the Atlanta Falcons 1978 season?
CREATE TABLE "schedule" (
  "game" real,
  "date" text,
  "opponent" text,
  "result" text,
  "falcons_points" real,
  "opponents" real,
  "record" text,
  "attendance" real
);
SELECT COUNT("opponents") FROM "schedule" WHERE "record"='6-4';