Write down the power set of the set ${0}.$

If the number of elements in a set $A$ is $n(A) = 40$,$n(B) = 26$,and $n(A \cap B) = 16$,then what is the value of $n(A \cup B)$?

Two newspapers $A$ and $B$ are published in a city. It is known that $25\%$ of the city population reads $A$ and $20\%$ reads $B$, while $8\%$ reads both $A$ and $B$. Further, $30\%$ of those who read $A$ but not $B$ look into advertisements, $40\%$ of those who read $B$ but not $A$ look into advertisements, and $50\%$ of those who read both $A$ and $B$ look into advertisements. Then the percentage of the population who look into advertisements is:

In a certain town,$25\%$ of the families own a phone and $15\%$ own a car; $65\%$ families own neither a phone nor a car and $2,000$ families own both a car and a phone. Consider the following three statements:
$(A) \, 5\%$ families own both a car and a phone
$(B) \, 35\%$ families own either a car or a phone
$(C) \, 40,000$ families live in the town
Then,

If $A = \{a, b\}$,$B = \{2, 3, 5, 6, 7\}$ and $C = \{5, 6, 7, 8, 9\}$,find $A \times (B \cap C)$.

If $A=\{1,2,3\}, B=\{2,3,4\}, C=\{1,3,4\}$ and $D=\{2,4,5\},$ then $(A \times B) \cap (C \times D) =$