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

Let $X = \{n \in N : 1 \leq n \leq 50\}$. If $A = \{n \in X : n \text{ is a multiple of } 2\}$ and $B = \{n \in X : n \text{ is a multiple of } 7\}$,then the number of elements in the smallest subset of $X$ containing both $A$ and $B$ is

In an examination,$40 \%$ students failed in Hindi,$50 \%$ students failed in English. If $21 \%$ students failed in both the subjects,find the percentage of those who passed in Hindi.

$A - (A - B)$ is equal to:

The range of $f(x) = \cos x - \sin x$ is

If ${N_a} = \{an : n \in N\}$,then ${N_5} \cap {N_7} = $