In question 8, there is a polygon ABCD, where
A = (4, 0)
B = (6, -3)
C = (1, -2)
D = (2, 1)
We need to reflect it at the line y = -3
Then the x-coordinate of each point does not change, only the y-coordinates of the points will change
The vertical distance between each point and the line y = -3 will equal the vertical distance between their images and the line y = -3
Let us draw them
The polygon A'B'C'D' is the image of the polygon ABCD by reflection about the black line y = -3
Since the distance between the x-axis and the line y = -3 is 3 units, then the y-coordinates of each point will subtract from -6 except the point that lies on the line y = -3 as point B
A' = (4, -6 - 0) = (4, -6)
B' = (6, -3) = (6, -3)
C' = (1, -6 - (-2)) = (1, -6 + 2) = (1, -4)
D' = (2, -6-1) = (2, -7)