a) [tex]\frac{7}{9}+\frac{4}{9}=\frac{7+4}{9}=\frac{11}{9}=\boxed{1\frac{2}{9}}[/tex]
b) [tex]\frac{5}{7}+\frac{6}{7}=\frac{5+6}{7}=\frac{11}{7}=\boxed{1\frac{4}{7}}[/tex]
c) [tex]2\frac{2}{5}+\frac{4}{5}=2\frac{2+4}{5}=2\frac{6}{5}=\boxed{3\frac{1}{5}}[/tex]
