Ответ:

  1. \(1\frac{1}{2}=\frac{1\cdot2+1}{2}=\frac{3}{2}\).
  2. \(3\frac{2}{7}=\frac{3\cdot7+2}{7}=\frac{23}{7}\).
  3. \(5\frac{12}{25}=\frac{5\cdot25+12}{25}=\frac{137}{25}\).
  4. \(20\frac{4}{9}=\frac{20\cdot9+4}{9}=\frac{184}{9}\).

Ответ: 1) \(\frac{3}{2}\); 2) \(\frac{23}{7}\); 3) \(\frac{137}{25}\); 4) \(\frac{184}{9}\).