[tex]\cfrac{map}{actual}\qquad \stackrel{ratio}{\stackrel{cm}{1}:\stackrel{km}{25000}}\qquad \cfrac{1}{25000},\qquad \cfrac{9}{a}=\cfrac{1}{25000}\implies \cfrac{9\cdot 25000}{1}=a \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill 225000~km s~\hfill[/tex]