7. Determine the number of students in cultural activity

In a class, all the students take part in either music or drama or both. In which 21 students take part in music, 36 students take part in drama, and 9 students take part in both music and drama.

 

(i) The number of students who take part in only music is students.
(ii) The number of students who take part in the only drama is students.
(iii) The total number of students in the class is students.