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

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

The simplified switching circuit for the following circuit is

The simplified switching circuit for the following circuit is

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