Ответ:

  1. \(\frac{5b}{14x}\cdot\frac{7}{10}=\frac{35b}{140x}=\frac{b}{4x}\). Соответствие: \(\frac{b}{4x}\).
  2. \(\frac{5a}{6b}:\frac{15a^2}{4}=\frac{5a}{6b}\cdot\frac{4}{15a^2}=\frac{20a}{90a^2b}=\frac{2}{9ab}\). Соответствие: \(\frac{2}{9ab}\).
  3. \(\frac{4n^2}{3m^2}\cdot\frac{9m}{2n}=\frac{36n^2m}{6m^2n}=\frac{6n}{m}\). Соответствие: \(\frac{6n}{m}\).
  4. \(\frac{x^2}{6y}:\frac{xy}{12}=\frac{x^2}{6y}\cdot\frac{12}{xy}=\frac{2x}{y^2}\). Соответствие: \(\frac{2x}{y^2}\).

Ответ: \(\frac{5b}{14x}\cdot\frac{7}{10}\) — \(\frac{b}{4x}\); \(\frac{5a}{6b}:\frac{15a^2}{4}\) — \(\frac{2}{9ab}\); \(\frac{4n^2}{3m^2}\cdot\frac{9m}{2n}\) — \(\frac{6n}{m}\); \(\frac{x^2}{6y}:\frac{xy}{12}\) — \(\frac{2x}{y^2}\).