Table schema:
CREATE TABLE table_name_80 (viewers__m_ VARCHAR, rank__night_ VARCHAR, timeslot VARCHAR)

Question: What is the total number of Viewers with a Rank (Night) of n/a, and a Timeslot of 8:30 p.m.?
SQL: SELECT COUNT(viewers__m_) FROM table_name_80 WHERE rank__night_ = "n/a" AND timeslot = "8:30 p.m."