Tính rồi rút gọn 39/12 - 2

  $\frac{39}{12}$ - 2

= $\frac{39}{12}$ - $\frac{2 X 12}{12}$

= $\frac{39}{12}$ - $\frac{24}{12}$

= $\frac{39 - 24}{12}$

= $\frac{15}{12}$

= $\frac{15 : 3}{12 : 3}$

= $\frac{5}{4}$