Relational Algebra Question

Hey guys, I am studying for an Exam, and was hoping for some guidance on a particular Relational Algebra question I am not sure on.

Scenario:

Consider the database schema on the relations (where key attributes have been underlined):

COURSES(Number, Faculty, CourseName)
STUDENTS(RegNumber, Surname, FirstName, Faculty)
EXAMS(Student, Course, Grade, Date)

NOTE: relation EXAMS stores the registration number (attribute Student) of students that passed the exam for a given course (attribute Course is the number of course, not the name of the course), the grade and the date of the exam.

Question:

Formulate in relational algebra the query that retrieves for every course number in the Science faculty, the registration number and surname of students who passed the exam for such a course during the period 01/05/2010-15/05/2010.

My Answer

PROJECT Number, RegNumber, Surname (RESTRICT date > 30/04/2010 AND date < 16/05/2010 AND Grade > ‘E’(Courses JOIN r.number=Course Exams AND Students JOIN r.RegNumber = Student Exams))

Do you guys think my answer is correct? If not, what should I change? Thanks:)