Bài 44 :
$\dfrac{4}{7}$ `=` $\dfrac{4×3 }{7×3}$ `=` $\dfrac{12}{21}$
$\dfrac{8}{12}$ `=` $\dfrac{8:4}{12:4}$ `=` $\dfrac{2}{3}$
$\dfrac{...}{11}$ `=` $\dfrac{10:5}{55:5}$ `=` $\dfrac{2}{11}$
$\dfrac{...}{32}$ `=` $\dfrac{21}{24}$ `=` $\dfrac{21:3}{24:3}$ `=` `7/{8}` `=` $\dfrac{7×4}{8×4}$ `=` `28/{32}`
`->` Vậy chọn đáp án : A . $\text{12;2;2;28}$