Use the following three relations for this homework: Students (sid, sname, age) Courses (cid, cname, dept) Take (sid, cid, grade) 1. Write relational algebraic expressions for the following queries: Find names of all courses taken by the students . Find names of students who took all courses offered by the "CS" department whose name is Joe' Find names of 20-year-old students who have taken a "CS" course Write Domain Relational Calculus (DRC) expressions for the above queries. Use the following abbreviations for this question: Students (SI, SN, SA), Courses(CI, CN, CD), Take(SID, CID, CG) 2