Odpowiedź:
[tex]1\dfrac{4}{13}-\dfrac{9}{13}=\dfrac{1\cdot13+4}{13}-\dfrac{9}{13}=\dfrac{13+4}{13}-\dfrac{9}{13}=\dfrac{17}{13}-\dfrac{9}{13}=\boxed{\frac{8}{13}}\\\\\\6\dfrac{8}{9}-4\dfrac{2}{3}=6\dfrac{8}{9}-4\dfrac{2\cdot3}{3\cdot3}=6\dfrac{8}{9}-4\dfrac{6}{9}=\boxed{2\frac{2}{9}}[/tex]
