\newproblem{
\FPsetpar{a}{12}{15}
\FPsetpar{b}{13}{15}
\FPsetpar{c}{2}{4}
\FPsetpar{k}{4}{5}
\begin{problem}[4]
  $a=\a$, $b=\b$, $c=\c$, $k=\k$

Evaluate $\a-\c=$\fillin[b]{1cm}{$\FPsv{a-c}$}  $ \b:\k$ with two exact decimals \fillin[b]{1cm}{$\FPsv[2]{b/k}$} and $\k^{\c}$=\fillin{20pt}{$\FPsv{k^c}$}
 \end{problem}
 }
\newproblem{
\FPsetpar{a}{12}{15}
\FPsetpar{b}{13}{15}[\a]
\FPsetpar{c}{2}{4}
\FPsetpar{k}{4}{5}[\c]
\begin{problem}[4]
  $a=\a$, $b=\b$, $c=\c$, $k=\k$

If $A=\left\{a,b,c,d,\a,\c,\k\right\}$ and $B=\left\{c,a,\c,1,\b\right\}$ then \\
 $A\cup B=$\fillin[u]{4cm}{$\left\{a,b,c,d,\a,\c,\k,\b,1\right\}$}\\
 $ A\cap B=$\fillin[u]{4cm}{$\left\{a,c,\c\right\}$} \\
 $A\setminus B$=\fillin{60pt}{$\left\{b,d,\k\right\}$}
 \end{problem}
 }