If $X$ and $Y$ are two sets such that $X \cup Y$ has $18$ elements,$X$ has $8$ elements,and $Y$ has $15$ elements,how many elements does $X \cap Y$ have?

If $A$ and $B$ are finite sets and $A \subset B$,then

If $A$ and $B$ are two sets such that $n(A) = 0.16$,$n(B) = 0.14$,and $n(A \cup B) = 0.25$,then $n(A \cap B)$ is equal to:

Two dice are thrown. The events $A, B$ and $C$ are as follows:
$A:$ getting an even number on the first die.
$B:$ getting an odd number on the first die.
$C:$ getting the sum of the numbers on the dice $\leq 5$.
Describe the event $A \cap B^{\prime} \cap C^{\prime}$.

If $A = \{3, 5, 7, 9, 11\}$,$B = \{7, 9, 11, 13\}$,$C = \{11, 13, 15\}$,and $D = \{15, 17\}$,find $(A \cap B) \cap (B \cup C)$.

If $A = \{1, 2, 3\}$ and $B = \{3, 8\}$,then find $(A \cup B) \times (A \cap B)$.