Mẫu số chung : `45`
`4/9=(4xx5)/(9xx5)=20/45`
`3/5=(3xx9)/(5xx9) = 27/45`
Vậy.....
\(\dfrac{\text{4 }}{9}=\)\(\dfrac{\text{ 4 x 5 }}{9x5}=\) \(\dfrac{\text{20}}{45}\)
\(\dfrac{\text{3}}{5}=\) \(\dfrac{\text{3 x 9 }}{5x9}=\) \(\dfrac{\text{27 }}{45}\)
\(\dfrac{4}{9}=\dfrac{4x5}{9x5}=\dfrac{20}{45}\)
\(\dfrac{3}{5}=\dfrac{3x9}{5x9}=\dfrac{27}{45}\)