Question 1202817
<pre>
1. (X v B) --> ~J       Premise
2. S --> J              Premise
3. X                    Premise
// show ~S 
4. X v B                3, Addition (ADD)
5. ~J                   4,1,  Modus Ponens (MP)
6. ~S                   5,2,  Modus Tollens (MT)
** Done **