2)

[tex] \frac{9}{11} + ( - \frac{2}{5} ) = \frac{9}{11} - \frac{2}{5} = \frac{45}{55} - \frac{22}{55} = \frac{23}{55} [/tex]

4)

[tex] - 8 \frac{9}{14} + 3 \frac{3}{7} = - 8 \frac{9}{14} + 3 \frac{6}{14} = - 5 \frac{3}{14} [/tex]

8)

[tex] - 11 \frac{7}{9} + 8 \frac{2}{15} = - 11 \frac{35}{45} + 8 \frac{6}{45} = - 3 \frac{29}{45} [/tex]

12)

[tex] - 3 \frac{8}{9} + ( - 2 \frac{1}{12} ) = - 3 \frac{8}{9} - 2 \frac{1}{12} = - 3 \frac{32}{36} - 2 \frac{3}{36} = - 5 \frac{35}{36} [/tex]