8) (410 - d) : 7 + 70 = 120

Решение:

1. \[ (410 - d) : 7 + 70 = 120 \]
2. \[ (410 - d) : 7 = 120 - 70 \]
3. \[ (410 - d) : 7 = 50 \]
4. \[ 410 - d = 50 \times 7 \]
5. \[ 410 - d = 350 \]
6. \[ -d = 350 - 410 \]
7. \[ -d = -60 \]
8. \[ d = 60 \]

Ответ: d = 60