# Mathematical formula alignment

I am trying to align my formulas and at the end of each formula I want to see number. Since I would like to explain all formulas in my report. However after making following changes, I got so many errors not only related with the file that I have worked also another files even I did not make changes. I am a bit confused. Could you please check this:

\begin{align}
$processTime& = (U / calcRate_{byte/s}) + (D / calcRate_{byte/s})$ \tag{1}\\[2ex]
$safetyTime& = (1.0 + safety)* processTime$ \tag{2}\\[2ex]
\end{align}


Here you are, I think. You don't have to add \tag, numbering is automatic. Also, don't add \\ at the end: it creates a new line and a new tag.

\documentclass[a4paper, 11pt]{book}
\usepackage[utf8]{inputenc}
\usepackage{fourier, heuristica} % not necessary, just personal preference
\usepackage{mathtools}

\begin{document}

\begin{align}
\text{processTime}& = (U / \text{calcRate}_\text{\,byte/s}) + (D / \text{calcRate}_\text{\,byte/s})\\[2ex]
\text{safetyTime}& = (1.0 + \text{safety})* \text{processTime}
\end{align}

\end{document}


• I would use something like \newcommand*\mvar{\mathrm} and then use \mvar{processTime}, \mvar{calcRate}, etc. Apart from that I don't know why \\[2ex] I think \\ looks just fine. (And, ideally, may be even load siunitx and set it up so one could use \si{\byte\per\second} but that might just be an overkill.) – Manuel Feb 6 '16 at 12:57
• Thank you for the answer. However the tag number seen like 5.1, 5.2 . Could we avoid chapter number? Because I just want to see tag number like 1, 2, 3, etc. – limonik Feb 6 '16 at 13:43