I want to add equation in which there is an explanation of what means the symbols used in the equation. So far, I have this

And I want to have somethihg like this:

My MWE is:

\documentclass{book}
\usepackage[utf8]{inputenc}
\begin{document}
$$Umsatz = V_{R} \times R_{Zeit} \times R_{Konz} \times \dot{c}$$

With

\begin{table}[h!]
\begin{tabular}{cc}
Umsatz & total mass flow converted during the reaction in {kmol/h} \\
$V_{R}$ & Catalyst volume in $m^{3}$
\end{tabular}
\end{table}
\end{document}


• Off topic : never use table wan you do't need a float ! tabular or tabularx, or the alignments structures of amsmath/mathtools (as shown below) will do the job. – Jhor Aug 22 '18 at 20:27

A possible solution with alignat andfleqn from nccmath: which places equation environments at the left margin (with a cusstomisable distance from the left margin). I took the liberty to replace ‘with’ by ‘where’, which is better style. Also units are not typed in italic; to have a correct formatting of units, use the siunitx package:

\documentclass{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{array}
\usepackage{mathtools, nccmath}
\usepackage{siunitx}

\begin{document}

\begin{fleqn}
\begin{alignat}{2}
& \text{Kinetic } & \quad & \mathit{Umsatz} = V_{R} \cdot R_\text{Zeit} \cdot R_\text{Konz} \cdot \dot{c} \\[1.5ex]
& \text{where} & &
\begin{tabular}[t]{@{}r <{:}@{\space}l}
$\mathit{Umsatz}$ & total mass flow converted during the reaction in \si{kmol/h} \\
$V_{R}$ & Catalyst volume in \si{m^{3}}
\end{tabular} \notag
\end{alignat}
\end{fleqn}

\end{document}


• :\,\space seems like overkill and also the extra space in \text{Kinetic }. On another note, despite that _\text{...} works, I thought we should encourage users to write _{\text{...}}. ;-) Also, why not use \cdot instead of \times as shown in the picture from the OP? – Ruixi Zhang Aug 22 '18 at 20:24
• You're right, I removed \,. As to \times I guess I was looking at the other picture. 'Tis fixed. Thank you for pointing these inconsistencies! – Bernard Aug 22 '18 at 20:31
• Thanks! It worked! iIs there any way to add a line break without adding to the second line the ":" at the beginning? – user151562 Aug 23 '18 at 7:26
• I'm not too sure exactly what you're referring to. Do you mean you'd like to have ‘Umsatz:’ with a colon and ‘$V_R$’ without? – Bernard Aug 23 '18 at 7:48