Combined events and Venn diagrams: If $A$ and $B$ satisfy these conditions what is $P(A \cap B')$? Events $A$ and $B$ satisfy $P((A \cup B)') = 0.2$ and $P(A) = P(B) = 0.5$. Find $P(A \cap B')$. 

Here's some potentially useful formulae
$P(A'\cap B')=P((A\cup B)')$
$P(A')=1-P(A)$
$P(A|B)=\frac{P(A\cap B)}{P(B)}$
