$\large{\text{Ta có:}}$
$\text{$\left(\dfrac{2}{3}\right)^{13}:\left(\dfrac{8}{9}\right)^{7}$}$
$\text{$=\left(\dfrac{2}{3}\right)^{13}.\left(\dfrac{9}{8}\right)^{7}$}$
$\text{$=\dfrac{2^{13}.9^7}{3^{13}.8^7}$}$
$\text{$=\dfrac{2^{13}.(3^2)^7}{3^{13}.(2^3)^7}$}$
$\text{$=\dfrac{2^{13}.3^{14}}{3^{13}.2^{21}}$}$
$\text{$=\dfrac{2^{13}.3^{14}}{2^{21}.3^{13}}$}$
$\text{$=\dfrac{3}{2^{8}}$}$
$\text{$=\dfrac{3}{256}$}$
