
Subtract 3 from both sides,

Let x = X and y - 3 = Y
Then,

So, we have shifted the origin to a point (0, 3).
This is an odd function and the graph of an odd function is symmetrical about the origin.
That is, symmetrical about X = 0, Y = 0
Symmetrical about x = 0,, y - 3 = 0
Symmetrical about x = 0, y = 3.
Hence, the graph is symmetrical about the point (0, 3).