What is Viewers, when 18-49 is "N/A", and when Weekly Winner is "Wedding DJ Chris Dixon"?
CREATE TABLE "ratings_and_results" (
  "air_date" text,
  "rating" text,
  "18_49" text,
  "viewers" text,
  "weekly_winner" text
);
SELECT "viewers" FROM "ratings_and_results" WHERE "18_49"='n/a' AND "weekly_winner"='wedding dj chris dixon';