Ответ:

  1. \(6 \cdot x = 42\)
    \(x = 42 : 6 = 7\)
  2. \(x : 7 = 4\)
    \(x = 4 \cdot 7 = 28\)
  3. \(112 : x = 7\)
    \(x = 112 : 7 = 16\)
  4. \(x \cdot 6 = 252\)
    \(x = 252 : 6 = 42\)

Ответ: 7; 28; 16; 42.