Sets

If $$\displaystyle A=\left \{ 2, 4 \right \}$$ and  $$B\left \{ 3, 4, 5 \right \},$$ then $$\displaystyle \left ( A\cap B \right )\times \left ( A\cup B \right )$$ is
What is the cardinality of the set of odd positive integers less than $$10$$?
Examine whether $$A=$$ $$\{$$ $$x:x$$ is a positive integer divisible by $$3 \}$$ is a subset of $$B=$$ $$\{$$ $$x:x$$ is a multiple of $$5$$, $$x\in N$$ $$\}$$.
Which one of the following is an example of non-empty set?