What is the relational algebra from the question below. I already have the SQL and need it in relational algebra.

Student (snum: integer, sname: string, major: string, level: string, age: integer)

Class (name: string, meets_at: time, room: string, fid: integer)

Enrolled (snum: integer, cname: string)

Faculty (fid: integer, fname: string, deptid: integer)

3. Find the names of all classes that either meet in room R128 or have five or more students enrolled.

SQL:

SELECT C.name

FROM Class C

WHERE C.room = R128

OR C.name IN (SELECT E.cname

FROM Enrolled E

GROUP BY E.cname

HAVING COUNT (*) >= 5);