The equation (x+6)^2+(y+4)^2=36 models the position and range if the source of a radio signal

The complete question is
The equation (x + 6)^2 + (y + 4)^2 = 36 models the position and range of the source of a radio signal. Describe the position of the source and the range of the signals

we know that
the equation of the circle is of the form
(x-h)²+(y-k)²=r²
where
(h,k) is the center of the circle
and
r is the radius
in the equation
(x + 6)² + (y + 4)²= 36> (x + 6)² + (y + 4)²= 6²
the center is the point (-6,-4)
and the radius is equal to 6 units
so
in this problem
the source would be the center of the circle which is (-6,-4) and the range would be the radius  which is  6

The answer is (a) 12-2(-1)(6)2(6)=12