Ответ:

  1. \(x + 6 = 49\)
    \(x = 49 - 6\)
    \(x = 43\)
  2. \(y - 50 = 28\)
    \(y = 28 + 50\)
    \(y = 78\)
  3. \(74 - x = 30\)
    \(x = 74 - 30\)
    \(x = 44\)

Ответ: x = 43; y = 78; x = 44.