How many destinations have a weekly frequency and are named AC Express?
CREATE TABLE "important_originating_express_trains" (
  "train_no" text,
  "train_name" text,
  "destination" text,
  "category" text,
  "frequency" text
);
SELECT COUNT("destination") FROM "important_originating_express_trains" WHERE "frequency"='Weekly' AND "train_name"='AC Express';