Unless otherwise specified we usually assume the dilation is about the origin. That is you can tell the scale factor by the way the distance to the origin changes.
Point C, for example, is 6 units from the origin. Its image, C' is 4 units from the origin. Then the scale factor image/original is 4/6 = 2/3.
Your green question mark gets filled with 3 to make the fraction 2/3.
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To find the translation, pick any point on A'B'C' and find the corresponding point A'', B'', or C''. Count the squares you have to go left to get from A' to A'', for example. That will be 5 to the left. Similarly, count the squares you have to go down to get from A' to A''. That will be 4 down.
