Ответ:

  1. 1 1/2 = 3/2; 3/2 · 2/3 = 1.
  2. 2 1/4 = 9/4; 9/4 · 4/9 = 1.
  3. 1 2/5 = 7/5; 7/5 · 5/7 = 1.