How to use a new enumeration command for exercise together enumerate and hyperref commands?

Question

I have been using a good command to enumerate my exercise list's. But now I would like the exercise number appeared in the enumeration list in addition with hyperref command. How could to do this? Is it possible? Thanks a lot.

Here is a minimum example.

\documentclass[a4paper,brazil, 12pt]{report}%{\article}
\usepackage{amsmath,amsfonts,amscd,bezier}
\usepackage{amssymb}
\usepackage{babel}
\usepackage[latin1]{inputenc}
\usepackage{color}
\usepackage{hyperref}
\usepackage[shortlabels]{enumitem}
\usepackage{multicol}
\usepackage{tasks}


\newcounter{theeq} \setcounter{theeq}{0}
\newcommand{\eq}{ 
    \

    \noindent 
    \refstepcounter{theeq}\textbf{\arabic{theeq}}. }


\begin{document}

\eq {\label{eq1}} Let $f: \mathbb{R} \to \mathbb{R}$ a function
\begin{enumerate}[$(\ref{eq1}. \ a)$, leftmargin=3.0em]
    \item {\label{eq1a}} Prove that...
    \item Next ...
\end{enumerate}

\eq XXXX
\begin{enumerate}[$(a)$, leftmargin=3.0em]
    \item Prove that...
    \item Next ...
\end{enumerate}

\eq Consider in exercise \ref{eq1a} bla bla bla.

\end{document}

Answer 1

Nesting levels is what lists do best. (Not just a crutch for the counting impaired.)

\documentclass[a4paper,brazil, 12pt]{report}%{\article}
\usepackage{amsmath,amsfonts,amscd,bezier}
\usepackage{amssymb}
\usepackage{babel}
\usepackage[latin1]{inputenc}
\usepackage{color}
\usepackage{hyperref}
\usepackage{enumitem}
\usepackage{multicol}
\usepackage{tasks}

\setlist[enumerate,2]{label = (\theenumi.\alph*),ref = (\theenumi.\alph*)}

\begin{document}

\begin{enumerate}
\item Let $f: \mathbb{R} \to \mathbb{R}$ a function
\begin{enumerate}
    \item \label{eq1a}Prove that...
    \item Next ...
\end{enumerate}

\item XXXX
\begin{enumerate}
    \item Prove that...
    \item Next ...
\end{enumerate}

\item Consider in exercise \ref{eq1a} bla bla bla.
\end{enumerate}

\end{document}

---

This version creates a new list for exercises.

\documentclass[a4paper,brazil, 12pt]{report}%{\article}
\usepackage{amsmath,amsfonts,amscd,bezier}
\usepackage{amssymb}
\usepackage{babel}
\usepackage[latin1]{inputenc}
\usepackage{color}
\usepackage{hyperref}
\usepackage{enumitem}
\usepackage{multicol}
\usepackage{tasks}

\newlist{exercise}{enumerate}{2}
\setlist[exercise,1]{label = \arabic*.,ref = \arabic*)}
\setlist[exercise,2]{label = (\arabic{exercisei}.\alph*),ref = (\arabic{exercisei}.\alph*)}

\begin{document}

\begin{exercise}
\item Let $f: \mathbb{R} \to \mathbb{R}$ a function
\begin{exercise}
    \item \label{eq1a}Prove that...
    \item Next ...
\end{exercise}

\item XXXX
\begin{exercise}
    \item Prove that...
    \item Next ...
\end{exercise}

\item Consider in exercise \ref{eq1a} bla bla bla.
\end{exercise}

\begin{enumerate}
\item Normal enumerate
\begin{enumerate}
\item Second level
\end{enumerate}
\end{enumerate}

\end{document}