[tex]\displaystyle\bf\\\frac{a}{c} =b \ \ \Rightarrow \ \ a=bc\\\\\\\frac{1}{b} =\frac{c}{z} \ \ \Rightarrow \ \ z=bc\\\\\\\frac{a}{z} =\frac{bc}{bc} =1\\\\\\Otvet \ : \ \frac{a}{z} =1[/tex]