Ответ:

  1. \[\frac{x}{y^2}=\frac{xy^6}{y^8}.\]
  2. \[\frac{a}{3b}=\frac{2ab^2}{6b^3}.\]
  3. \[\frac{9}{4m^2n}=\frac{27mn}{12m^3n^2}.\]
  4. \[\frac{11c}{15d^6}=\frac{22bcd}{30bd^7}.\]