[tex] - 1 \frac{7}{9} + ( - 2 \frac{11}{12} ) = - 1 \frac{28}{36} - 2 \frac{33}{36} = - 3 \frac{61}{36} = - 4 \frac{25}{36} [/tex]

[tex]6 \frac{1}{6} + ( - 2 \frac{2}{7} ) = 6 \frac{1}{6} - 2 \frac{2}{7} = 6 \frac{7}{42} - 2 \frac{12}{42} = 5 \frac{49}{42} - 2 \frac{12}{42} = 3 \frac{37}{42} [/tex]