Great, and how many courses are there in Arts?
SELECT COUNT ( * )  FROM Courses AS T1 JOIN Subjects AS T2 ON T1.subject_id   =   T2.subject_id WHERE T2.subject_name  =  "Arts"
number of courses in Arts refers to COUNT(*) where subject_name = 'Arts'; JOIN operation is used to connect Courses table with Subjects table on subject_id.