CREATE TABLE table_73645 ("WEEK" FLOAT, "Sydney" FLOAT, "Melbourne" FLOAT, "Brisbane" FLOAT, "Adelaide" FLOAT, "Perth" FLOAT, "TOTAL" FLOAT, "WEEKLY RANK" FLOAT)

How many episodes aired in Sydney in Week 3?
SELECT COUNT("Sydney") FROM table_73645 WHERE "WEEK" = '3'
SELECT COUNT("Sydney") FROM "table_73645" WHERE "WEEK" = '3'