If $A$ and $B$ are any two sets, then $A \cap (A \cup B)$ is equal to

State whether each of the following statement is true or false. Justify you answer.

$\{2,3,4,5\}$ and $\{3,6\}$ are disjoint sets.

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?

Let $A$ and $B$ be two sets such that $n(A) = 0.16,\,n(B) = 0.14,\,n(A \cup B) = 0.25$. Then $n(A \cap B)$ is equal to

Using that for any sets $\mathrm{A}$ and $\mathrm{B},$

$A \cup(A \cap B)=A$

If $A$ and $B$ are not disjoint sets, then $n(A \cup B)$ is equal to