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 $$1.\ S\rightarrow T$$ $$2.\ \sim T$$ $$3.\ (\sim S\vee U)\rightarrow R$$ $$4.\ R\rightarrow (P\cdot \sim Q)$$ $$/ \therefore P\vee Q$$ $$5.\ \sim S$$ 1, 2 Modus Tollens $$6.\ \sim S \vee U$$ 5 Addition $$7.\ R$$ 3, 6 Modus Ponens $$8.\ P \cdot \sim Q$$ 4, 7 Modus Ponens $$9.\ P$$ 8 Simp. $$10.\ P\vee Q$$ 9 Add.