答案1
嗯,我不太明白你在做什么,结果和图片上不完全一样:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{enumerate}
\setcounter{enumi}{12}
\item
\begin{enumerate}
\item Let $H, N$ be normal subgroups of a finite group $G$. Assume that the
order
\item Let $H_{1},\dots, H_{r}$ be normal subgroups of $G$ such that the
order of $H_{i}$ is rel
\end{enumerate}
\end{enumerate}
\end{document}