If $A = \{ 2,\,4,\,5\} ,\,\,B = \{ 7,\,\,8,\,9\} ,$ then $n(A \times B)$ is equal to

If the set $A$ has $p$ elements, $B$  has $q$ elements, then the number of elements in $A × B$ is

If $R$ is the set of all real numbers, what do the cartesian products $R \times R$ and $R \times R \times R$ represent?

If $(1, 3), (2, 5)$ and $(3, 3)$ are three elements of $A × B$ and the total number of elements in $A \times B$ is $6$, then the remaining elements of $A \times B$ are

If $A \times B=\{(a, x),(a, y),(b, x),(b, y)\} .$ Find $A$ and $B$

If $A = \{1, 2, 4\}, B = \{2, 4, 5\}, C = \{2, 5\},$ then $(A -B) × (B -C)$ is