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I want to prepare a book with many chapters (and sections), notes, exercises and linked solutions at the end of the book . I decided to adopt the example from on matching enumerated exercises with their answer. However, I want to display points per question part as shown here . The exam package

documentclass{memoir}

usepackage{amsmath}
usepackage[inline]{enumitem}
usepackage{xcolor}
usepackage{ntheorem}
theorembodyfont{upshape}
theoremseparator{.}

usepackage{answers}
Newassociation{sol}{Solution}{ans}
renewcommand{Solutionlabel}[1]{small{#1.}}
newtheorem{ex}{}[section]
renewcommand{theex}{arabic{ex}}
newenvironment{Ex}[1]{begin{trivlist}item textsc{#1} %
renewcommand{Currentlabel}{#1}}{end{trivlist}}

usepackage{multicol}
newenvironment{mtmulticols}[1]{%
Writetofile{ans}{stringbegin{multicols}{#1}}
begin{multicols}{#1}}{end{multicols}%
Writetofile{ans}{stringend{multicols}}}

Newassociation{solitem}{Solutionsubitem}{ans}
renewcommand{Solutionsubitemlabel}[1]{#1}
newenvironment{Solutionsublist}{Writetofile{ans}{stringbegin{Solution} {theex}}}{Writetofile{ans}{stringend{Solution}}}

begin{document}
chapter{Polynomials}
section{Partial fractions}
label{sec:partial-fractions}
tracingmacros=1
Opensolutionfile{ans}[partial-fractions]
section*{Exercises for Section ref{sec:partial-fractions}}
vspace{-0.6cm}
hrulefill
begin{Ex}{Warm-ups}
end{Ex}
begin{ex}
Who is the most famous mathematician of all time?
begin{sol}
Euler
end{sol}
end{ex}
begin{ex}
Resolve each of the following proper rational expressions (some filler here) into partial fractions.
begin{multicols}{3}
begin{Solutionsublist}
begin{enumerate}[label=(alph*)]
item $displaystyle{frac{1}{(x - 1)(x - 2)}}$
begin{solitem}
$displaystyle{frac{1}{x - 2} - frac{1}{x - 1}}$
end{solitem}
item $displaystyle{frac{5x + 4}{x^2 + x - 2}}$
begin{solitem}
$displaystyle{frac{2}{x + 2} + frac{3}{x - 1}}$
end{solitem}
item $displaystyle{frac{7x - 1}{2x^2 - x - 1}}$
begin{solitem}
$displaystyle{frac{3}{2x + 1} + frac{2}{x - 1}}$
end{solitem}
item $displaystyle{frac{25}{18x^3 - 9x^2 - 11x + 2}}$
begin{solitem}
$displaystyle{frac{3}{3x + 2} - frac{12}{6x - 1} + frac{1}{x -
1}}$
end{solitem}
item $displaystyle{frac{x^2 + 15x - 4}{(x + 1)(x + 2)(x - 8)}}$
begin{solitem}
$displaystyle{frac{2}{x - 8} + frac{2}{x + 1} - frac{3}{x +
2}}$
end{solitem}
item $displaystyle{frac{48}{(x^2 - 1)(x^2 - 9)}}$
begin{solitem}
$displaystyle{frac{3}{x - 1} + frac{3}{x + 1} - frac{1}{x + 3}
+ frac{1}{x - 3}}$
end{solitem}
end{enumerate}
end{Solutionsublist}
end{multicols}
end{ex}

Closesolutionfile{ans}
section*{Answers for Section ref{sec:partial-fractions}}
input{partial-fractions}

end{document}