What number is halfway between -5 and -9.2?

Pentagon abcde is dilated according to the rule do,3(x,y) to create the image pentagon a'b'c'd'e', which is shown on the graph. what are the coordinates of point a of the pre-image? a) (-1, 1)b) (-1, 2)c) (-9, 6)d) (-9, 18)