Please answer the following queries in Relational Algebra expressions:

This is the relation schema(all attributes are strings except for degrees and score):

Student(s-ID, s-Name, s-Dept, s-Degree:integer, advisor-ID)

Lecture(L-ID, L-Name, L-Dept, L-Degree:integer, p-ID)

Register(s-ID, L-ID, score:integer)

Professor(p-ID, name)

Question: Find the names of students who register for every lecture of the Business department. Also, Find the names of students who got the highest score in the Economics' lecture.