Ответ:
\(\frac{3}{7}:\frac{9}{14}=\frac{3}{7}\cdot\frac{14}{9}=\frac{2}{3}\).
\(5-(2.8-\frac{2}{3})\cdot1.5=5-\frac{32}{15}\cdot\frac{3}{2}=5-\frac{16}{5}=\frac{9}{5}=1.8\).
Ответ: 1,8.
\(\frac{3}{7}:\frac{9}{14}=\frac{3}{7}\cdot\frac{14}{9}=\frac{2}{3}\).
\(5-(2.8-\frac{2}{3})\cdot1.5=5-\frac{32}{15}\cdot\frac{3}{2}=5-\frac{16}{5}=\frac{9}{5}=1.8\).
Ответ: 1,8.