Bài 1:
$a)\frac{11}{18}=$ $\frac{22}{36};$ $\frac{5}{9}=$ $\frac{20}{36};$ $\frac{7}{12}=$ $\frac{21}{36}$
$b)\frac{31}{48}=$ $\frac{31}{48};$ $\frac{5}{16}=$ $\frac{15}{48};$ $\frac{11}{16}=$ $\frac{33}{48}$
$c)\frac{7}{-25}=$ $\frac{-21}{75};$ $\frac{1}{15}=$ $\frac{5}{75};$ $\frac{1}{3}=$ $\frac{25}{75}$
$d)\frac{19}{22}=$ $\frac{57}{66};$ $\frac{5}{6}=$ $\frac{55}{66};$ $\frac{-29}{33}=$ $\frac{-58}{66}$
Bài 4:
$a)\frac{-4}{17}=$ $\frac{-24}{102}$
$b)\frac{-14}{35}>$ $\frac{-26}{65}$ (mình không chắc nhé)
Chúc bạn học tốt!