% This file is public domain
\begin{defproblem}{sample}
\begin{onlyproblem}
Differentiate $y=\sin x$
\end{onlyproblem}
\begin{onlysolution}
$y'=\cos x$
\end{onlysolution}
\end{defproblem}

\begin{defproblem}[1]{sample2}
\begin{onlyproblem}
Differentiate $y = \sin(#1x)$
\end{onlyproblem}
\begin{onlysolution}
$y'=#1\cos #1x$
\end{onlysolution}
\end{defproblem}

\begin{defproblem}{sample3}
\begin{onlyproblem}
Differentiate $y = x^2$.
\end{onlyproblem}
\begin{onlysolution}
$y' = 2x$
\end{onlysolution}
\end{defproblem}