a, 0,5$\frac{0,5}{-10,78}$  = $\frac{1,54}{3,5}$ 

$\frac{3,5}{10,78}$ =$\frac{1,54}{-0,5}$

$\frac{-0,5}{-1,54}$ =$\frac{-10,78}{3,5}$

$\frac{3,5}{-1,54}$ =$\frac{-10,78}{-0,5}$ 

b, $\frac{4,86}{21,6}$ =$\frac{-9,3}{-11,34}$ 

$\frac{-11,34}{21,6}$ = $\frac{-9,3}{4,86}$

$\frac{21,6}{-11,34}$ =$\frac{4,86}{-9,3}$

$\frac{21,6}{4,48}$ =$\frac{-11,34}{9,3}$

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