\[ \text { (3) Given: } \begin{aligned} & d \rightarrow e \\ & d \vee f \\ & h \rightarrow \sim e \\ & h \end{aligned} \] Prove: \( f \)

Step 1 ：\(1. h \rightarrow \sim e \) (Given)

Step 2 ：\(2. h \) (Given)

Step 3 ：\(3. \sim e \) (1, 2, Modus Ponens)

Step 4 ：\(4. d \rightarrow e \) (Given)

Step 5 ：\(5. \sim d \) (3, 4, Modus Tollens)

Step 6 ：\(6. d \vee f \) (Given)

Step 7 ：\(7. f \) (5, 6, Disjunctive Syllogism)