How many matches did Rajasthan Royals play in Season 8?
 Season 8 refers to Season_Id = 8
SELECT SUM(CASE WHEN T1.Season_Id = 8 THEN 1 ELSE 0 END) FROM `Match` AS T1 INNER JOIN Team AS T2 ON T1.Team_1 = T2.Team_Id OR T1.Team_2 = T2.Team_Id WHERE T2.Team_Name = 'Rajasthan Royals'