Question 1141207
<pre>

1.  A → ~B
2.  ~ (C • ~A)                               /C → ~B

3.  ~C ∨ ~~A            2, deMorgan's law
4.  ~C ∨ A              3, double negation
5.  C → A               4, material equivalence
6.  C → ~B              5,1, hypothetical syllogism

Edwin</pre>