Intersections:

It is performed by 'min' operation.

i.e. $A \cap B=\mu_A(x) \cap \mu_B(x)\\ =min(\mu_A(x),\mu_B(x))\\ \forall x \in X$

Example:

$A=\{10,20,30,40,50\}\\ B=\{15,22,26,35,45\}\\ A \cap B=\{min(10,15),min(20,22),min(30,26),min(40,35),min(50,45)\}\\ =\{10,20,26,35,45\}$

Union:

It is performed by 'max' operation.

i.e. $A \cup B=\mu_A(x) \cup \mu_B(x)\\ =max(\mu_A(x),\mu_B(x))\\ \forall x \in X$ 

Example:

$A=\{10,20,30,40,50\}\\ B=\{15,22,26,35,45\}\\ A \cup B=\{max(10,15),max(20,22),max(30,26),max(40,35),max(50,45)\}\\ =\{15,22,30,40,50\}$