b) 9 : 4 32 : 5 18 : 5

b)

          $\begin{array}{l}\begin{array}{c}9\\ \underset{¯}{8}\end{array}\begin{array}{c}4\\ 2\end{array}\\ 1\end{array}$                                        $\begin{array}{l}\begin{array}{c}32\\ \underset{¯}{30}\end{array}\begin{array}{c}5\\ 6\end{array}\\ 02\end{array}$                                      $\begin{array}{l}\begin{array}{c}18\\ \underset{¯}{15}\end{array}\begin{array}{c}5\\ 3\end{array}\\ 03\end{array}$             

9 : 4 = 2 (dư 1)                          32 : 5 = 6 (dư 2)                         18 : 5 = 3 (dư 3)