how to culculate this question

#maaf jika salah semoga membantu

1. z = 6
2. u = 8
3. y = 35
4. x = 16
5. b = 56
6. y = 12
7. c = 30
8. b = 15
9. y = 81
10. u = 35
11. y = 14
12. z = 14
13. a = 20
14. c = 54
15. y = 8

cara dan jawaban ada di foto