The scale factor of a dilation is the ratio of the corresponding side lengths of the dilated and original figures. In this case, the red triangle is dilated to twice its original size, so the scale factor is 2.
This can be seen by comparing the corresponding side lengths of the two triangles:
Original triangle (AABC):
AB = 10
BC = 12
CA = 15
Dilated triangle (AA'B'C'):
A'B' = 20
B'C' = 24
C'A' = 30
As you can see, each side length of the dilated triangle is twice as long as the corresponding side length of the original triangle. Therefore, the scale factor of the dilation is 2.
This is also consistent with the red color indicating that the triangle has been upscaled by a factor of 2.