Official solution
Given hyperbola : \[{{{x^2}} \over {{a^2}}} - {{{y^2}} \over 9} = 1\]
\[\because\] It passes through \[(8,3\sqrt 3 )\]
\[\because\] \[{{64} \over {{a^2}}} - {{27} \over 9} = 1 \Rightarrow {a^2} = 16\]
Now, equation of normal to hyperbola
\[{{16x} \over 8} + {{9y} \over {3\sqrt 3 }} = 16 + 9\]
\[ \Rightarrow 2x + \sqrt 3 y = 25\] ...... (i)
\[\left( { - 1,9\sqrt 3 } \right)\] satisfies (i)