我很难将文本和方程式对齐。我不知道该使用哪个包。抱歉，我列出代码的方式不是最好的。这是我第一次进入这个论坛。这是我最终的 pdf 的图片：
以下是我针对该图片编写的代码：
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{enumerate}
\item{
\begin{equation}
\begin{aligned}
& x-2x+4-6x \\
& = x-2x-6x+4 & \text{Rearrange the terms} \\
& = -x-6x+4 & \text{Subtraction (for x)} \nonumber \\
& = -7x+4 & \text{Subtraction (for x)}
\end{aligned}
\end{equation}}
\item{
\begin{equation}
\begin{aligned}
& 2x-5(5+2)^2+3x \\
& = 2x+3x - 5(5+2)^2 & \text{Rearrange the terms} \\
& = 5x-5(5+2)^2 & \text{Addition (for x)} \\
& = 5x-5(7)^2 & \text{Parantheses} \nonumber \\
& = 5x - 5(49) & \text{Exponent} \\
& = 5x - 245 & \text{Multiplication}
\end{aligned}
\end{equation}}
\item{
\begin{equation}
\begin{aligned}
& 6x+5x+11x+12+14x \\
& = 6x+5x+11x+14x+12 & \text{Rearrange the terms} \\
& = 11x+11x+14x+12 & \text{Addition (for x)} \\
& = 22x + 14x +12 & \text{Addition (for x)} \\
& = 36x +12 & \text{Addition (for x)} \nonumber \\
\end{aligned}
\end{equation}}
\item{
\begin{equation}
\begin{aligned}
& 5+12+5x-15x+10 \\
& = 5x-15x+5+12+10 & \text{Rearrange the terms} \\
& = -10x+5+12+10 & \text{Subtraction (for x)} \\
& = -10x+17+10 & \text{Addition} \\
& = -10x+27 & \text{Addition} \nonumber \\
\end{aligned}
\end{equation}}
\end{enumerate}
\end{document}
答案1
如果您想要延续对齐，最简单的方法是定义您自己的环境：
\documentclass{article}
\usepackage[pass,showframe]{geometry} % just to show the page margins
\usepackage{amsmath}
\makeatletter
\newenvironment{multialign} % a copy of flalign*
{\setcounter{multialign}{0}%
\def\item{\refstepcounter{multialign}\themultialign.\qquad}%
\start@align\tw@\st@rredtrue\m@ne}
{\endalign}
\makeatother
\newcounter{multialign}
\allowdisplaybreaks
\begin{document}
\begin{multialign}
\item
& x-2x+4-6x & && \\
& = x-2x-6x+4 & \text{Rearrange the terms} && \\
& = -x-6x+4 & \text{Subtraction (for $x$)} && \\
& = -7x+4 & \text{Subtraction (for $x$)} && \\
\item
& 2x-5(5+2)^2+3x & && \\
& = 2x+3x - 5(5+2)^2 & \text{Rearrange the terms} && \\
& = 5x-5(5+2)^2 & \text{Addition (for $x$)} && \\
& = 5x-5(7)^2 & \text{Parantheses} && \\
& = 5x - 5(49) & \text{Exponent} && \\
& = 5x - 245 & \text{Multiplication} && \\
\item
& 6x+5x+11x+12+14x & && \\
& = 6x+5x+11x+14x+12 & \text{Rearrange the terms} && \\
& = 11x+11x+14x+12 & \text{Addition (for $x$)} && \\
& = 22x + 14x +12 & \text{Addition (for $x$)} && \\
& = 36x +12 & \text{Addition (for $x$)} && \\
\item
& 5+12+5x-15x+10 & && \\
& = 5x-15x+5+12+10 & \text{Rearrange the terms} && \\
& = -10x+5+12+10 & \text{Subtraction (for $x$)} && \\
& = -10x+17+10 & \text{Addition} && \\
& = -10x+27 & \text{Addition} &&
\end{multialign}
\end{document}
答案2
\documentclass[preview,border=12pt,12pt]{standalone} % disable this line and change to the article below.
%\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{enumitem}
\setlist[enumerate,1]{itemsep=12pt,label=\textbf{\arabic*.},start=9}
\begin{document}
\begin{enumerate}
% One ----------------
\item
$\!
\begin{aligned}[t]
x-2x+4-6x
&= x-2x-6x+4 && \text{Rearrange the terms} \\
&= -x-6x+4 && \text{Subtraction (for $x$)} \\
&= -7x+4 && \text{Subtraction (for $x$)}
\end{aligned}
$
% Two ----------------
\item
$\!
\begin{aligned}[t]
x-2x+4-6x
&= x-2x-6x+4 && \text{Rearrange the terms} \\
&= -x-6x+4 && \text{Subtraction (for $x$)} \\
&= -7x+4 && \text{Subtraction (for $x$)}
\end{aligned}
$
\end{enumerate}
\end{document}
