\newproblem{
\begin{problem}[3]
\FPsetpar{a}{2}{5}
\FPsetpar{b}{3}{5}
\FPsetpar{c}{\a}{8}

  $a=\a$, $b=\b$, $c=\c$

\pair{$\a+\b$}{$\FPsv{a+b}$}
\pair{$\c-\a$}{$\FPsv{c-a}$}
\pair{$\a \times \b$}{$\FPsv{a*b}$}

\matching
\end{problem}
 }

\newproblem{
\begin{problem}[3]
\FPsetpar{a}{12}{15}
\FPsetpar{b}{13}{15}
\FPsetpar{c}{2}{4}
\FPsetpar{k}{3}{5}
  $a=\a$, $b=\b$, $c=\c$
  
\pair{$\FPsv{k*a}:\a$}{$\k$}
\pair{$\k^{\c}$}{$\FPsv{k^c}$}
\pair{$\a \times \b$}{$\FPsv{a*b}$}
\pair{$\a \times \b$}{$\FPsv{a*b}$}
\pair{$\a \times \b$}{$\FPsv{a*b}$}
\matching
\end{problem}
 }
