The number of subgroups of the group $(Z_{5}, +_{5})$ is

In the following,state whether $A = B$ or not:
$A = \{2, 4, 6, 8, 10\}$; $B = \{x : x \text{ is a positive even integer and } x \le 10\}$

Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$10 \dots A$

Two dice are thrown. The events $A, B$ and $C$ are as follows:
$A:$ getting an even number on the first die.
$B:$ getting an odd number on the first die.
$C:$ getting the sum of the numbers on the dice $\leq 5$.
Describe the event $B$ or $C$.

Write the set $A = \{ 1, 4, 9, 16, 25, \dots \}$ in set-builder form.

If $A = \{x \in R : x^2 - 5|x| + 6 = 0\}$,then find $n(A)$.