Ответ:

  1. \(321+(x+13)=450\)

    \(x+13=450-321=129\)

    \(x=129-13=116\)

  2. \(122+(y-7)=200\)

    \(y-7=200-122=78\)

    \(y=78+7=85\)

  3. \(204-(x+29)=100\)

    \(x+29=204-100=104\)

    \(x=104-29=75\)

  4. \(53-(y-13)=24\)

    \(y-13=53-24=29\)

    \(y=29+13=42\)

Ответ: 1) \(x=116\); 2) \(y=85\); 3) \(x=75\); 4) \(y=42\).