Question 1022576
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 1. F v (G & S)
 2. ~ (I v S)      // F & F

 3. (F v G) & (F v S)        1, Distribution
 4. (F v S) & (F v G)        3, Commutation
 5. F v S                    4, Simplification
 6. ~I & ~S                  2, DeMorgan's law
 7. ~S & ~I                  6, Commutation
 8. ~S                       7, Simplification
 9. S v F                    5, Commutation
10. F                        8, Disjunctive Syllogism
11. F & F                    10,10, Conjunction

Edwin</pre>