Let $A$ and $B$ be subsets of a set $X$. Then
$A - B = A \cup B$
$A - B = A \cap B$
$A - B = {A^c} \cap B$
$A - B = A \cap {B^c}$
If $X=\{a, b, c, d\}$ and $Y=\{f, b, d, g\},$ find
$X-Y$
If $S$ and $T$ are two sets such that $S$ has $21$ elements, $T$ has $32$ elements, and $S$ $\cap \,T$ has $11$ elements, how many elements does $S\, \cup$ $T$ have?
If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find
$A \cup C$
If $A, B$ and $C$ are non-empty sets, then $(A -B) \cup (B -A)$ equals
If $A=\{3,6,9,12,15,18,21\}, B=\{4,8,12,16,20\},$ $C=\{2,4,6,8,10,12,14,16\}, D=\{5,10,15,20\} ;$ find
$B-D$