Which time has a local/networked value of Local, ad frequency of every 20 minutes, and news frequency of n/a after 7PM news?
CREATE TABLE "saturday_and_sundays_programming_as_of_s" (
  "time" text,
  "show_name" text,
  "local_networked" text,
  "ad_freq" text,
  "news_freq" text
);
SELECT "time" FROM "saturday_and_sundays_programming_as_of_s" WHERE "local_networked"='local' AND "ad_freq"='20 minutes' AND "news_freq"='n/a after 7pm news';