Sets

If $$n(A)=4,n(B)=3,n(A\times B\times C)=24$$, then $$n(C)=$$

Given $$\mu  = $${$$x / x$$ is an integer, $$x \in [-4,6] $$},
$$P' = \left\{-4, -3, 0, 1, 2, 4, 6\right\}$$
$$Q' = \left\{-3, -2, 1, 3, 6\right\}$$
For each of the following sets, state with reasons with reasons whether it is a null set.
Given, universal set = {$$x$$ : $$x \,\,\epsilon\,\, N$$, $$10 \leq x \leq 35$$}, A = {$$x \,\,\epsilon\,\,N$$ : $$x \leq 16$$} and B = {$$x$$ : $$x > 29$$}. Find :
If $$A = \{1, 2, 3, 4, 5\}, B = \{2, 4, 6, 8\}$$ and $$\{3,4,5,6\}$$; verify :