If a set $A$ has $n$ elements,then the total number of subsets of $A$ is

Show that $A \cup B = A \cap B$ implies $A = B$.

Make correct statements by filling in the symbols $\subset$ or $\not\subset$ in the blank spaces:
$\{a, b, c\} \dots \{b, c, d\}$

Let $A = \{a, e, i, o, u\}$ and $B = \{a, b, c, d\}$. Is $A$ a subset of $B$? No. (Why?). Is $B$ a subset of $A$? No. (Why?)

Write the following interval in set-builder form: $[6, 12]$

Given the sets $A = \{1, 3, 5\}$,$B = \{2, 4, 6\}$ and $C = \{0, 2, 4, 6, 8\}$,which of the following may be considered as a universal set for all the three sets $A$,$B$ and $C$?