In a class of $70$ students, each student passed Hindi or English. Of them, $15$ students passed both Hindi and English and $40$ students passed Hindi. Find the number of students who passed English.

In a school, there are $150$ students. If $90$ of them play chess, $70$ of them play both chess and carrom, and $40$ play none of these games, then find the number of children who play only carrom.

If $A=\left\{2, 3, 4\right\}$ and $B=\left\{3, 5\right\}$, then $A \cap B$ has only one element

If $A=\left\{1, 2, 3, 4, 5\right\}$, then $2\in A$

If $A=\left\{1, 2, 3\right\}$ and $B=\left\{2, 4\right\}$, then $A\cup B$ has $5$ elements

If $A\subset B$, then $B\cap A=B$

If $A\subseteq B and B\subseteq A$, then $A=B$

If $\mu =\left\{1, 2, 3, 4, 5, 6, 7, 8\right\}$ and $A=\left\{2, 5, 8\right\}$, then find $n\left(A^{\text{'}}\right)$

If $X=\left\{Non-prime numbers\right\}$ and $Y=\left\{Non-composite numbers\right\}$, then $n\left(X\cap Y\right)=$_____