In the diagram,
the points A, B and C lie on the straight line y = 2x – 1
The coordinates of A are (2, 3).
The coordinates of B are (5, 9).
Given that AC = 3AB, find the coordinates of C
I did 5-2 =3 and then 9-3 = 6 and then multiplied them by 3 to get 9,18, however, the mark scheme says the answer is 11,21 and I do not understand how they worked it out.
Thank you.