First

Exercise 1 An exercise with a solution.
$\begin{solution} This is a solution. \relax{} \end{solution}$

Exercise 2 An exercise with a hint and a secret solution.
$\begin{hint} This is a hint. \end{hint}$

$\begin{Solution} This is a secret solution. \end{Solution}$

Exercise 3 An exercise with a hint.
$\begin{hint} This is a hint. \end{hint}$

test test testtwo testtwo