1)[tex]- \frac{7}{30} ( -\frac{5}{7})= \frac{7*5}{30*7} = \frac{1}{6} [/tex]
2)[tex] \frac{1}{18} : (-\frac{1}{9})= \frac{1}{18}*(-\frac{9}{1})=-\frac{9*1}{18*1}=-\frac{1}{2}[/tex]
3)[tex]\frac{1}{6}-\frac{1}{2}=\frac{1}{6}-( \frac{1}{2})^3=\frac{1}{6}-\frac{3}{6}= -\frac{2}{6} [/tex]
