Вот ответы для каждого уравнения: 1. c - 8 = 7 → c = 15. 2. 40 - b = 40 → b = 0. 3. x + 75 = 100 → x = 25. 4. x - 12 = 22 → x = 34. 5. 63 - c = 0 → c = 63. 6. b + 7 = 23 → b = 16. 7. 100 - y = 90 → y = 10. 8. 97 + c = 98 → c = 1. 9. 18 + b = 30 → b = 12. 10. c + 40 = 100 → c = 60. 11. b - 75 = 25 → b = 100. 12. a = 9. 13. 17 - a = 50 → a = -33.