1)
[tex]\frac{2}{9}+\frac{3}{6}=\frac{2}{9}+\frac{3:3}{6:3}=\frac{2}{9}+\frac{1}{2}=\frac{2\cdot2}{9\cdot2}+\frac{1\cdot9}{2\cdot9}=\frac{4}{18}+\frac{9}{18}=\frac{13}{18}\\[/tex]
2)
[tex]\frac{1}{8}+\frac{7}{6}=\frac{1}{8}+1\frac{1}{6}=\frac{1\cdot3}{8\cdot3}+1\frac{1\cdot4}{6\cdot4}=\frac{3}{24}+1\frac{4}{24}=1\frac{7}{24}\\[/tex]
3)
[tex]\frac{1}{8}+\frac{3}{4}=\frac{1}{8}+\frac{3\cdot2}{4\cdot2}=\frac{1}{8}+\frac{6}{8}=\frac{7}{8}\\[/tex]
