My question states: Given sets A and B, show that A \ (A ∩ B) = (A ∪ B) \ B.
This is where I got to before I got stuck: $$x \; \in \; A \; \setminus \; (A∩B)$$ $$x \; \in \; A \quad and \quad \notin \; (A∩B)$$ $$x \; \in \; A \quad and \quad (x \notin A \; or \; x \notin \; B)$$ $$ x \; \in \; A \quad and \quad x \; \notin \; B$$
....
$x \in A$ and $x \not \in B$
($x \in A$ or $x \in B$) and $x\not \in B$
$x \in (A\cup B)\setminus B$.
$A\setminus(A\cap B) \subset (A\cup B)\setminus B$
..........
And if
$x \in (A\cup B) \setminus B$ then
($x\in A$ or $x \in B$) and $x \not \in B$
$x\in A$ and $x \not \in B$
$x\in A$ and ($x \not \in A$ or $x\not \in B$)
$x\in A$ and $x \not \in A\cap B$
$x \in A\setminus (A\cap B)$.
$A\setminus(A\cap B) \supset (A\cup B)\setminus B$
So
$A\setminus(A\cap B) = (A\cup B)\setminus B$