Which proportions show that the triangles are not similar?

Answer:
AC and DF
Step-by-step explanation:
We can see that the triangles have a scale factor of 3.
1 * 3 = 3 (AB and DE)
2 * 3 = 6 (BC and EF)
However...
2 * 3 = 6 not 7 (AC and DF)