SAT Circles Question

Circle A in the xy-plane has the equation $(\mathrm{x}+8{)}^2+(\mathrm{y}-8{)}^2=25$ . Circle B has the same center as circle A. The radius of circle B is two times the radius of circle A. The equation defining circle Bin the xy-plane is $(\mathrm{x}+8{)}^2+(\mathrm{y}-8{)}^2=k$ , where kis a constant. What is the value ofk?