\[\begin{array}{l}
A = \left\{ {x \in Z|\,\,x = 10k\,\,\,\left( {k \in Z} \right)} \right\}\\
B = \left\{ {x \in Z|\,\,x = 5m,\,\,\,x = 2n,\,\,\,m,\,\,n \in Z} \right\}\\
\left\{ \begin{array}{l}
x\,\, \vdots \,\,5\\
x\,\, \vdots \,\,2
\end{array} \right. \Rightarrow x\,\, \vdots \,\,10 \Rightarrow B = \left\{ {x \in Z|\,\,x = 10k\,\,\,\left( {k \in Z} \right)} \right\}\\
\Rightarrow A\,\, = B.
\end{array}\]
