[tex]a) \: 2 \frac{5}{7} + 1 \frac{2}{5} = 2 \frac{25}{35 } + 1 \frac{14}{35} = 3 \frac{39}{35} = 4 \frac{4}{35} [/tex]
[tex]b) \: 5 \frac{5}{7} - 2 \frac{1}{5} = 5 \frac{25}{35} - 2 \frac{7}{35} = 3 \frac{18}{35} [/tex]
[tex]c) \: 6 \frac{2}{9} - 4 \frac{3}{7} = 6 \frac{14}{63} - 4 \frac{27}{63} = 1 \frac{50}{63} [/tex]
