
$\begin{aligned}
& \frac{a+0}{3}=h \Rightarrow a=3 h \
& \frac{9+0}{3}=k \Rightarrow k=3 \
& \because(h, k)=\left(\frac{6+10 \cos \alpha-10 \sin \alpha}{3}, \frac{8-10 \sin \alpha-10 \cos \alpha}{3}\right) \
& 6+10 \cos \alpha-10 \sin \alpha=3 h \
& 10 \cos \alpha-10 \sin \alpha=3 h-6 \
& 10(\cos \alpha-\sin \alpha)=1 \
& \frac{8-10 \sin \alpha+10 \cos \alpha}{3}=k \
& \Rightarrow 100 \sin 2 \alpha=99 \
& h=\frac{7}{3} \
& \Rightarrow a=7
\end{aligned}\text { Now, } 5 a-3 h+6 k+100 \sin 2 \alpha=35-7+18+99=145$