Official solution
\[p \Leftrightarrow (q \Rightarrow p)\]
\[ \sim (p \Leftrightarrow (q \Leftrightarrow p))\]
\[ \equiv p \Leftrightarrow \, \sim (q \Rightarrow p)\]
\[ \equiv p \Leftrightarrow (q \wedge \sim p)\]
\[ \equiv (p \Rightarrow (q \wedge \sim p)) \wedge ((q \wedge \sim p) \Rightarrow p))\]
\[ \equiv ( \sim p \vee (q \wedge \sim p)) \wedge (( \sim q \vee p) \vee p))\]
\[ \equiv (( \sim p \vee q) \wedge \sim p) \wedge ( \sim q \vee p)\]
\[ \equiv \sim p \wedge ( \sim q \vee p)\]
\[ \equiv ( \sim p \wedge \sim q) \vee ( \sim p \wedge p)\]
\[ \equiv ( \sim p \wedge \sim q) \vee c\]
\[ \equiv ( \sim p \wedge \sim q)\]