If $X=\{a, b, c, d\}$ and $Y=\{f, b, d, g\},$ find

$X \cap Y$

If $A=\{3,5,7,9,11\}, B=\{7,9,11,13\}, C=\{11,13,15\}$ and $D=\{15,17\} ;$ find

$A \cap C \cap D$

Let $A =\{1,2,3,4,5,6,7\}$ and $B =\{3,6,7,9\}$. Then the number of elements in the set $\{ C \subseteq A : C \cap B \neq \phi\}$ is

If the sets $A$ and $B$ are defined as $A = \{ (x,\,y):y = {1 \over x},\,0 \ne x \in R\} $ $B = \{ (x,y):y =  - x,x \in R\} $, then

If $A = \{ x:x$ is a natural number $\} ,B = \{ x:x$ is an even natural number $\} $ $C = \{ x:x$ is an odd natural number $\} $ and $D = \{ x:x$ is a prime number $\} ,$ find

$A \cap B$

Consider the following relations :

$(1) \,\,\,A - B = A - (A \cap B)$

$(2) \,\,\,A = (A \cap B) \cup (A - B)$

$(3) \,\,\,A - (B \cup C) = (A - B) \cup (A - C)$

which of these is/are correct