What are the coordinates of r' after dilation by a scale factor of 3, centered at the origin, followed by translation (x,y)->(x+4,y)?
a) r'(3x + 4, 3y)
b) r'(3x + 12, 3y)
c) r'(3x, 3y)
d) r'(3x + 4, 3y + 4)