[tex] \frac{5}{9} - \frac{3}{9} = \frac{2}{3} [/tex]
[tex] \frac{7}{13} - \frac{5}{13 } = wiekszy \: o \: \frac{2}{13} [/tex]
[tex] \frac{3}{17} + \frac{2}{17} = \frac{5}{17} [/tex]
[tex] \frac{14}{21} - \frac{7}{21} = mniejszy \: o \: \frac{7}{21} [/tex]
