First reflect the graph in the x-axis, giving \(y=-f(x)\). Then translate it by \(\begin{pmatrix}0\\3\end{pmatrix}\), giving \(y=3-f(x)\).

An equivalent order is a translation by \(\begin{pmatrix}0\\-3\end{pmatrix}\), followed by reflection in the x-axis: \(-(f(x)-3)=3-f(x)\).