Final answer:
The transformation is a translation to the left and up.
Step-by-step explanation:
This transformation is a translation to the left and up. To find the translation, we subtract the x-coordinates and the y-coordinates of the two points.
The x-coordinate translation is: -12 - (-3) = -12 + 3 = -9, which means the translation is 9 units to the left.
The y-coordinate translation is: 21 - 10 = 11, which means the translation is 11 units up.
Therefore, the transformation is a translation to the left and up.