This is not what you want. I don't understand why in each line of cases, you use some text at the end of line. If so, you can use, for example $AB=CD$ \dotfill 1 point without using cases. In my answer, in the cases, I also use \dotfill for all lines.

\documentclass[a5paper]{book} \usepackage[top=1.8cm, bottom=2.7cm, left=2.7cm, right=1.8cm]{geometry} \usepackage{amsthm,amsmath} \begin{document} \begin{enumerate} \item $AB=CD$ \dotfill 1 point \item $AB=CD$ \dotfill 2 points \item $\begin{cases} GB=DE\\ AB=CD. \end{cases}$ \dotfill 2 points \end{enumerate} \end{document} 

An easy way to obtain the desired result, namely

is to use the tabularx environment (requires the tabularx package). Indeed, the above printout has been produced with the following code:

% My standard header for TeX.SX answers: \documentclass[a4paper]{article} % To avoid confusion, let us explicitly % declare the paper format. \usepackage[T1]{fontenc} % Not always necessary, but recommended. % End of standard header. What follows pertains to the problem at hand. \usepackage{amsmath} \usepackage{tabularx} \makeatletter \newcommand*\Annadotfill{% \leavevmode % Do you really want "\cleaders"? \cleaders \hb@xt@ .33em{\hss .\hss }\hfill \kern \z@ } \@ifdefinable\@Anna@brace@width{\newdimen\@Anna@brace@width} \settowidth\@Anna@brace@width{% $\left\{\vbox{\vskip \@m \p@}\right.\kern -\nulldelimiterspace$% } \newenvironment{Annacases}{% \left\{% \tabcolsep \z@ \def\arraystretch{1.2}% linespread: adjust as you please \tabularx{\dimexpr \linewidth-\@Anna@brace@width \relax}% {>{$}r<{$}>{${}}X<{$}}% }{% \endtabularx \right.% \kern -\nulldelimiterspace } \makeatother \begin{document} Some text before the enumeration. \begin{enumerate} \item $AB=CD$ \Annadotfill text; \item $AB=CD$ \Annadotfill longer text; \item $ \begin{Annacases} AB &= CD\Annadotfill\text{text;}\\ AB &= CD+EF+GH\Annadotfill\text{longer text;}\\ MN+XY &= PQ\Annadotfill\text{longer text, and more.} \end{Annacases} $ \end{enumerate} Some text after the enumeration. \end{document} 

However, there must be a more efficient method, using primitive TeX commands…

Previous Attempt, Which I Had Deleted

Something like this?

This is the code:

% My standard header for TeX.SX answers: \documentclass[a4paper]{article} % To avoid confusion, let us explicitly % declare the paper format. \usepackage[T1]{fontenc} % Not always necessary, but recommended. % End of standard header. What follows pertains to the problem at hand. \usepackage{mathtools} % also loads "amsmath" \makeatletter \newcommand*\annadotsfill{\leaders\hbox{.\,}\hskip 2em \@plus 1fill \relax} \newcases{annacases} {} % separation between columns {$\m@th\displaystyle\hfil##$} % left preamble {$\m@th\displaystyle{}##$} % right preambel {\lbrace}{.} % delimiters \makeatother \begin{document} Some text before the equation. \[ \begin{annacases} AB &= CD\annadotsfill\text{text}\\ AB &= CD+EF+GH\annadotsfill\text{longer text}\\ MN+XY &= PQ\annadotsfill\text{longer text, and more} \end{annacases} \] Some text after the equation. \end{document} 

Unfortunately, I cannot dwell on explanations right now; I’ll try to edit this answer later on.