Odpowiedź:
a) [tex]\frac{1}{4} - \frac{1}{6} = \frac{3}{12} - \frac{2}{12} = \frac{1}{12}[/tex]
b) [tex]\frac{3}{10} - \frac{1}{15} = \frac{9}{30} - \frac{2}{30} = \frac{7}{30}[/tex]
c) [tex]\frac{13}{27} - \frac{7}{18} = \frac{26}{54} - \frac{21}{54} = \frac{5}{54}[/tex]
d) [tex]\frac{7}{8} - \frac{7}{20} = \frac{35}{40} - \frac{14}{40} = \frac{21}{40}[/tex]