1. K⊃L 2. ∼(L•F) 3. F / ∼K 4. ~L∨~F 2, deMorgan's law 5. ~F∨~L 4, commutation 6. ~~F 3, double negation 7. ~L 5,6, disjunctive syllogism 8. ~K 1,7, modus tollens Edwin