This is part of Ivan's homework. A line segment, AB, goes from the point A(4, 7) to the point B(9, 3). AB is translated 3 squares left and 2 squares down. The image of AB is AB. Work out the coordinates of A' and B. Solution A' is at (7, 5). B' is at (12, 1). Ivan has worked out the coordinates of A' and B' incorrectly.
Explain the mistake that he has made.​