Ответ:

  1. а) \(\frac{3}{10}+1\frac{1}{2}=\frac{3}{10}+\frac{15}{10}=\frac{9}{5}\).
    \(\frac{5}{6}\cdot\frac{9}{5}=\frac{3}{2}=1\frac{1}{2}\).
  2. б) \(1\frac{1}{5}=\frac{6}{5}\), а \(\frac{3}{4}-\frac{1}{3}=\frac{5}{12}\).
    \(\frac{6}{5}\cdot\frac{5}{12}=\frac{1}{2}\).
  3. в) \(1\frac{2}{3}-\frac{5}{6}=\frac{5}{6}\).
    \(\frac{5}{6}\cdot18=15\).

Ответ: а) \(1\frac{1}{2}\); б) \(\frac{1}{2}\); в) \(15\).