What is the center of a circle given by the equation (x-3)2+(y-9)2=16

The answer is : y = - 1x + 28

how I did it

(x-3)2+(y-9)2=16

1x - 3 times 2 + 1y -9 times 2 = 16

1x - 6 + 1y -18 =16
      +6        +6

1x + 1y -12 = 16
             +12    +12

1x + 1y = 28
 -1x                -1x

1y = -1x + 28
/1       /1      /1

y = - 1x + 28 or y = - x + 28