Question 1210175
```
1.  (x)[(Ax ⦁ Bx) ⊃ Cx]      Premise
2.  ~(x)(Ax ⊃ Cx)          Premise
3.  (∃x)~(Ax ⊃ Cx)         QN 2
4.  ~(Aa ⊃ Ca)             EI 3
5.  ~( ~Aa ∨ Ca)            Impl 4
6.  Aa ⦁ ~Ca               DM 5
7.  Aa                      Simp 6
8.  ~Ca                     Simp 6
9.  (Aa ⦁ Ba) ⊃ Ca         UI 1
10. ~(Aa ⦁ Ba) ∨ Ca        Impl 9
11. ~(Aa ⦁ Ba)              DS 8, 10
12. ~Aa ∨ ~Ba              DM 11
13. ~Ba                     DS 7, 12
14. (∃x)~Bx                EG 13
15. ~(x)Bx                 QN 14
```