Question

The dashed triangle is the image of the pre-image solid triangle.

What is the scale factor used to create the dilation?

Answer 1

The scale factor  is 4.

Answer 2

see the attached figure with letters to better understand the problem  

we know that

the scale factor is equal to

$scale\ factor=\frac{A'B'}{AB}$ or  $scale\ factor=\frac{B'C'}{BC}$

we have

$A'B'=8\ units \\AB=2\ units$

substitute in the formula

$scale\ factor=\frac{8}{2}$

$scale\ factor=4$

therefore

the answer is

the scale factor is equal to $4$