DeMorgan's Law

Suppose you have two non mutually exclusive sets E or F.
DeMorgan’s Law:

\begin{equation} (E\ and\ F)^{C} = (E^{C}\ or\ F^{C}) \end{equation}

\begin{equation} (E\ or\ F)^{C} = (E^{C}\ and\ F^{C}) \end{equation}