Please help

Consider the following SQL query for the University example: SELECT facName, schedule SELECT facName, schedule FROM Faculty, Class, Enroll, Student WHERE lastName = 'Burns' AND firstName = 'Edward' AND Class.classNumber = Enroll.classNumber AND Faculty.facId = Class.facId AND Student.stuId = Enroll.stuId: a. Write an initial relational algebra expression for this query. b. Using equivalences of relational algebra expressions, rewrite your relational algebra expression in a more efficient form, if possible. Explain why the new expression is efficient