\newproblem{
\begin{problem*}[4]\estraialfa{4}{a,b,c,x,y,z}{element}Let $A=\{\elementi,\elementii,\elementiii\}$ and $B=\{\elementi,\elementiii,\elementiv\}$.
\begin{parts}
\item \PTs{2}
List (without repetition) the elements of the set $A\cup B$
\begin{solution}[3cm]
\[A \cup B=\left\{\elementi,\elementii,\elementiii,\elementiv\right\}\]
\end{solution}
\begin{workarea}{3cm}
$A \cup B=$
\end{workarea}
\item \PTs{2}
List (without repetition) the elements of the set $A\cap B$
\begin{solution}[3cm]
\[A \cap B=\left\{\elementi,\elementiii\right\}\]
\end{solution}
\begin{workarea}{3cm}
$A \cap B=$
\end{workarea}
\end{parts}
\end{problem*}
}