$\textit{Đáp án + Giải thích các bước giải:}$
$\text{8$\dfrac{1}{3}$ : 11$\dfrac{2}{3}$ = 13 : ($2x^{}$)}$
$\text{$\dfrac{25}{3}$ : $\dfrac{35}{3}$ = 13 : ($2x^{}$)}$
$\text{$\dfrac{25}{3}$ . $\dfrac{3}{35}$ = 13 : ($2x^{}$)}$
$\text{13 : $\dfrac{5}{7}$ = $2x^{}$}$
$\text{$2x^{}$ = 13 . $\dfrac{7}{5}$}$
$\text{$2x^{}$ = $\dfrac{91}{5}$}$
$\text{$x^{}$ = $\dfrac{91}{5}$ : 2 = $\dfrac{91}{10}$ . $\dfrac{1}{2}$}$
$\text{$x^{}$ = $\dfrac{91}{10}$}$