Remember the basic operations:
Complement
The complement of a set S is
consists of everything that is not in S.
Union
The union of two sets is everything
that is in either set; that is, anything colored (blue,
yellow, or green).
Intersection
The intersection of two sets is everything
that is in both sets; that is, anything colored both
blue and yellow, namely green.
Cardinality of Intersections and
Unions
The cardinality of an intersection is the number
of elements in the intersection.
The cardinality of a union is the sum of the
cardinalities of the given sets less the number of elements
in the intersection.