Find the equation of a circle concentric with the circle $x^2+y^2-6x+12y+15=0$ and has double of its area.

Question

[Hint:concentric circles have the same centre.]

$\begin{array}{1 1}x^2+y^2-6x+12y-30=0\\x^2+y^2-6x+12y+30=0\\x^2+y^2-6x+12y-15=0\\x^2+y^2-6x+12y-45=0\end{array}$