$\text{Giải thích các bước giải:}$
$\text{Ta có :}$
$\dfrac{31}{15} = 2\dfrac{1}{15}$
$\dfrac{23}{11} = 2\dfrac{1}{11}$
$\text{Do}$ $\dfrac{1}{11} > \dfrac{1}{15} ⇒ 2\dfrac{1}{11} > 2\dfrac{1}{15}$
$⇒ \dfrac{31}{15} < \dfrac{23}{11}$
$⇒ \dfrac{15}{31} > \dfrac{11}{23}$
$\text{Vậy}$ $\dfrac{15}{31} > \dfrac{11}{23}$
$\huge\text{Hk tốt !}$