[tex]\it \dfrac{3}{7}+\dfrac{2}{5}:\dfrac{4}{15}=\dfrac{3}{7}+\dfrac{2}{5}\cdot\dfrac{15}{4}=\dfrac{3}{7}+\dfrac{}{}\dfrac{3\not0}{2\not0}=\dfrac{^{2)}3}{\ 7}+\dfrac{^{7)}3}{\ 2}=\dfrac{27}{14}\\ \\ \\ \dfrac{8}{9}:\dfrac{4}{3}+\dfrac{2}{5}:\Big(-\dfrac{1}{10}\Big)=\dfrac{8}{9}\cdot\dfrac{3}{4}-\dfrac{2}{5}\cdot\dfrac{10}{1}=\dfrac{\ \ 24^{(12}}{36}-\dfrac{20}{5}=\dfrac{2}{3}-\ ^{3)}4==-\dfrac{10}{3}[/tex]
Fracția dată devine:
[tex]\it \dfrac{\dfrac{27}{14}}{-\dfrac{10}{3}}=-\dfrac{27}{14}\cdot\dfrac{3}{10}=-\dfrac{81}{140}[/tex]
