(i) $5 x+12 y=60$; (ii) $4 x^{2}+4 y^{2}-12 x-24 y-7=0$

$\begin{aligned} \text { দৃশ্যকল্প-১: } f(x, y) & =x^{2}+y^{2}-10 x+6 y+25 \\ g(x, y) & =x^{2}+y^{2}+6 x-6 y-31\end{aligned}$

$S_{1} \equiv x^{2}+y^{2}+6 x+2 y+6 ; S_{2} \equiv x^{2}+y^{2}+8 x+y-10$