If $A = \{x : x$ is a multiple of $4\}$ and $B = \{x : x$ is a multiple of $6\}$ then $A \cap B$ consists of all multiples of

Find the union of each of the following pairs of sets :

$A=\{1,2,3\}, B=\varnothing$ 

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

$X \cap Y$

If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find

$A \cup B \cup C$

Find the union of each of the following pairs of sets :

$A = \{ x:x$ is a natural number and $1\, < \,x\, \le \,6\} $

$B = \{ x:x$ is a natural number and $6\, < \,x\, < \,10\} $

$A-(A-B)$ is