a) 4 i 2/9
[tex]\frac{4}{9} + 3\frac{7}{9} = 4\frac{2}{9}[/tex]
b) 3 i 4/5
[tex]4\frac{2}{5} - \frac{3}{5} = 3\frac{7}{5} - \frac{3}{5} = 3 \frac{4}{5}[/tex]
