relational algebra and sql query simple question

Job ID: 32310451

Budget: $2 – $8 USD

ExtraCurriculum (Course_code, school, title, description)
Enrolls_in (Course_code, StudentID)
Student (StudentID, DOB, name, address, phone_no)
a) Use Relational Algebra to find students who are either enrolled
in ‘pottery classes’ or ‘self-defence classes’ using UNION.
b) Use Relational Algebra to find students who are not enrolled in
any extra curriculum courses.
c) Use SQL to list the students in alphabetical order who are
enrolled in more than 3 different kinds of extra curriculum
courses.

i need help with these questions they are really simple for 5$
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