State the number of athletes in the 1984 Summer Olympic Games who were more than 50 years old.
the 1984 Summer Olympic Games refer to games_name = '1984 Summer'; athletes more than 50 years old refer to person_id where age > 50;
SELECT COUNT(T2.person_id) FROM games AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.games_id WHERE T1.games_name = '1984 Summer' AND T2.age > 50