a)
$\frac{2}{-6}$ =$\frac{3}{-9}$
$\frac{-6}{2}$ =$\frac{-9}{3}$
$\frac{2}{-4}$ =$\frac{3}{-6}$
$\frac{-4}{2}$ =$\frac{-9}{3}$
b)
$\frac{1}{2}$ =$\frac{2}{8}$
$\frac{2}{1}$ =$\frac{8}{2}$
*Tìm x
$\frac{8}{5}$ =$\frac{-12}{x}$
`=>`8x=(-12)*5
`=>`8x=-60
`=>`x=-7,5