Centered equation in enumerate with custom labels

Question

So this is what I'm trying to get:

The problem is that I can't get the formula to center. So the code looks like this right now:

\usepackage{amsthm,amsmath,amssymb,mathtools}
\usepackage{enumitem}
\DeclareMathOperator{\imp}{\rightarrow}

\begin{document}

\begin{enumerate}
    \item[(KP)]  $\forall p(p\imp\Diamond Kp)$
\end{enumerate}

\end{document}

How do I get it to look like it does in the picture?

Answer 1

This may be what you are after:

\documentclass{article}
\usepackage[leqno]{amsmath}
\usepackage{amssymb}
\DeclareMathOperator{\imp}{\rightarrow}
\begin{document}
\begin{equation}
  \forall p(p\imp\Diamond Kp)\tag{KP}
\end{equation}
\end{document}