Official solution
\[((A \wedge(B \vee C)) \Rightarrow(A \vee B)) \Rightarrow A\]
\[ \equiv \] \[
[\sim(\mathrm{A} \wedge(\mathrm{B} \vee \mathrm{C})) \vee(\mathrm{A} \vee \mathrm{B})] \Rightarrow \mathrm{A}
\]
\[ \equiv \] \[
\sim(\sim(A \wedge(B \vee C)) \vee(A \vee B)) \vee A
\]
\[ \equiv \] \[
(A \wedge(B \vee C)) \wedge \sim(A \vee B) \vee A
\]
\[ \equiv \] \[
(f \vee A)=A
\]
\[
\therefore \text { Negation of statement }=\sim A
\]