[tex]a) \: 2 \frac{3}{20} + \frac{1}{4} = \frac{43}{20} + \frac{1}{4} = \frac{12}{5} = 2\frac{2}{5} [/tex]
[tex]\: 1\frac{5}{18} + 2\frac{4}{9} + \frac{5}{6} = \frac{23}{18} + \frac{22}{9} + \frac{5}{6} = \frac{41}{9} = 4\frac{5}{9} [/tex]
[tex]3\frac{1}{2} + 2\frac{3}{4} + 1\frac{1}{3} = (3 + 2 + 1) + ( \frac{1}{2} + \frac{3}{4} + \frac{1}{3} ) = 6 + \frac{19}{12} = 6 + 1\frac{7}{12} = 7\frac{7}{12} [/tex]
[tex]b) \: 2\frac{1}{20} - \frac{3}{4} = \frac{41}{20} - \frac{3}{4} = \frac{13}{10} = 1\frac{3}{10} [/tex]
[tex]1\frac{7}{18} - 2\frac{2}{9} = \frac{25}{18} - \frac{20}{9} = - \frac{5}{6} [/tex]
[tex]2\frac{1}{7} - 5\frac{2}{3} = \frac{15}{7} - \frac{17}{13} = - \frac{74}{21} [/tex]
Mam nadzieję, że pomogłem ;))
