Ответ:

  1. \(917 - 828 = 89\).
  2. \(218 - 159 = 59\).
  3. \(58 + 642 + 87 = 700 + 87 = 787\).
  4. \(89 + 372 + 28 = 89 + 28 + 372 = 117 + 372 = 489\).
  5. \(900 - 638 = 262\).
  6. \(604 - 187 = 417\).

Ответ: 89; 59; 787; 489; 262; 417.