Let \(X\) be a topological space and \(A\subseteq B\) subsets of \(X\). Then
\begin{equation*} \bar{A} \subseteq \bar{B}. \end{equation*}
Proof
According to (0x677afc5e)
we have \(A \subseteq \bar{B}\). Therefore, according to the definition
we obtain \(\bar{A} \subseteq \bar{B}\).