[tex]a)- \frac{3}{2}+ \frac{5}{6}\cdot( -\frac{2}{5})=- \frac{3}{2}+( -\frac{2}{6})})=- \frac{3}{2}+( -\frac{1}{2})= \frac{-6-3}{6} =- \frac{9}{6}=- \frac{3}{2} [/tex]
[tex]- \frac{7}{4}- \frac{9}{25}:( -\frac{3}{5})=- \frac{7}{4}- \frac{9}{25}\cdot( -\frac{5}{3})= \\ \\ - \frac{7}{4}+ \frac{9\cdot5}{25\cdot3}= -\frac{7}{4} + \frac{3}{5}= \frac{-20+21}{20}= \frac{1}{20} [/tex]
[tex]b)-\frac{25}{27}\cdot \frac{9}{3} - \frac{13}{20}\cdot( -\frac{5}{26})=- \frac{25}{9}+ \frac{1}{2\cdot4}=- \frac{25}{8}+ \frac{1}{8} = \frac{-200+9}{72}=- \frac{191}{72}[/tex]
