Adding line by line comments to math proofs

Question

Is it possible to add a line by line discussion of my proof? I'm using the Harvey Mudd college math template, so the fewest number of packages or class editing would be great.

I'm looking for the following:

equation line comment about the proof

3+x=4 we are trying to solve for x

x=4-3 Subtract 3 from both sides

x=1 x must be one

Answer 1

There are many ways to do this. Please review Herbert Voss's comprehensive review of mathematics in (La)TeX

But, one way is to use the align environment from the amsmath package:

Another option to consider is to use \intertext (or \shortintertext from the mathtools package which yields tighter spacing):

Code: align:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
    3+x &=4 && \text{we are trying to solve for } x\
    x &=4-3 && \text{Subtract 3 from both sides}\
    x &=1   && x \text{ must be one}
\end{align}
\end{document}

Code: \shortintertext:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align}
\shortintertext{We are trying to solve for $x$:}
    3+x &=4 \
\shortintertext{Subtract 3 from both sides:}
    x &=4-3 \
\shortintertext{Hence, $x$ must be one:}
    x &=1 
\end{align}
\end{document}