Official solution
\[\begin{aligned}
&\text { Equation of chord with given middle point }\\
&\begin{aligned}
& \mathrm{T}=\mathrm{S}_1 \\
& \Rightarrow \frac{3 \mathrm{x}}{25}+\frac{\mathrm{y}}{16}-1=\frac{9}{25}+\frac{1}{16}-1 \\
& 48 \mathrm{x}+25 \mathrm{y}=144+25 \\
& 48 \mathrm{x}+25 \mathrm{y}=169 \text { Ans. }
\end{aligned}
\end{aligned}\]