The binary operation $*$ for combining sets is defined as $A*B =(A\cup B) - (A\cap B)$.
Prove that $G$, consisting of the set of all subsets of a set $S$ (including the empty set and the set $S$ itself), together with the binary operation $*$, forms a group. You may assume that the associative property is satisfied.
Consider the set of all subsets of the natural numbers and solve the equation $\{1,2,4\}*X = \{3,4\}$.