Avec l'extension `exercise` :
\documentclass[11pt,a4paper,leqno,french]{report}
\usepackage[french]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[a4paper]{geometry}
\usepackage{amssymb,amsthm, amsmath,stmaryrd,thmtools}
\usepackage{hyperref}
\usepackage[answerdelayed]{exercise}
\renewcommand{\ExerciseName}{Exercice}
\renewcommand{\ExerciseHeader}{\textbf{\ExerciseName~\ExerciseHeaderNB\ExerciseHeaderTitle\ExerciseHeaderOrigin.}~}
\renewcommand{\AnswerHeader}{\textit{Solution de l'\ExerciseName\ \ExerciseHeaderNB~}}
\begin{document}
\chapter{Cours}
\begin{Exercise}[label=exo1]
calculer 2+2
\end{Exercise}
\begin{Answer}[ref=exo1]
ça vaut 4
\end{Answer}
\begin{Exercise}[label=exo2]
calculer 3+2
\end{Exercise}
\begin{Answer}[ref=exo2]
ça vaut 5
\end{Answer}
\chapter{Corrigé des exercices}
\shipoutAnswer
\end{document}
