The center of the circle x^2 + y^2 = 8x - 16y - 34 with equation is the point (x,y). What is x + y?
x^2 - 8x + y^2 + 16y = -34
(x - 4)^2 + (y + 8)^2 = -34 + 16 + 64 = 66
center: (4, -8)
x + y = 4 - 8 = -4
+1223 
