Ответ:

  1. 24 + x = 25
    x = 25 − 24
    x = 1.
  2. 18 : x = 3
    x = 18 : 3
    x = 6.
  3. 7 · x = 14
    x = 14 : 7
    x = 2.

Ответ: 1) x = 1; 2) x = 6; 3) x = 2.