Question 613312
<pre>
1. (R>S)
2. V v~S
3. ~V/.'.~R
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4. ~S            2,3   Disjunctive syllogism
5. ~R            1,4   Modus Tollens
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B)


<pre>

1. W.(XvY)
2. W
3. ~X/.'.YvZ
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4. (X v Y).W      1     Commutation
5. X v Y          4     Simplification
6. Y v X          5     Commutation
7. Y              6,3   Disjunctive syllogism
8. Y v Z          7     Addition

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C)

<pre>
1. A * ~ B / .'. B > C
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2. ~B * A           1    Commutation
3. ~B               2    Simplification
4. ~B v C           3    Addition
5. B > C            4    Material Implication
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