Ответ:

  1. \(3\frac{1}{12}-\frac{1}{6}=3\frac{1}{12}-\frac{2}{12}=2\frac{11}{12}\).
  2. \(8\frac{7}{30}-2\frac{9}{20}=6+\frac{14}{60}-\frac{27}{60}=5\frac{47}{60}\).