Math Mode – Coding an Equation with Description

Question

I want to code this equation in LaTeX:

I'd like to know how to code the equation and the description below it with a reference as well.

Answer 1

Even though your question was thoroughly answered here's my solution, it differs only in not using a table but a list:

\documentclass{article}

\usepackage{amsmath}
\usepackage{amssymb}

\usepackage{enumitem}

\begin{document}

\[ P_{xi}=\overline{U_{x}}+\sigma_{x}\frac{\sum^{Nu}_{k}D_{kx}\times 
    \left( \frac{S_{ki}-\overline{U_{k}}}{\sigma_{k}}\right)}{\sum^{Nu}_{k}D_{kx}} \]
Where:
\begin{itemize}[label=]
    \item $P_{xi}$: is the predicted rate for user $x$ on item $i$
    \item $S_{ki}$: is the rate of song $i$ given by user $k$
    \item $\overline{U_{x}}$: is the average rate of user $x$
    \item $\overline{U_{k}}$: is the average rate of user $k$
    \item $\sigma_{x}$: is the standard deviation of all the rates of user $x$
\end{itemize}

\end{document}

Which produces the following result: