SELECT statement using set Algebra

Question

Having these two tables:

DEPARTMENT

DNAME
-----------
RESEARCH
   IT
 SCIENCE

DEPTLOC

Answer 1

Set Algebra means using set operators: UNION, MINUS, INTERSECT.

Answer 2

If I where to guess you are asked to provide a solution using set operations like UNION, INTERSECT and DIFFERENCE (MINUS or EXCEPT). If A is departments located in Boston and B is departments located in London then (A - B) U (B - A) is one solution