bài 2
$\frac{-11}{-55}$ = $\frac{11}{55}$
$\frac{3}{-11}$ = $\frac{-3}{11}$
$\frac{-7}{-33}$ = $\frac{7}{33}$
$\frac{41}{-47}$ = $\frac{-41}{47}$
bài 3
$\frac{30}{-50}$ = $\frac{-3}{5}$
$\frac{1}{9}$ = $\frac{3}{27}$
$\frac{-2}{18}$ = $\frac{10}{-90}$