Question

The dashed-line triangle is a dilation image of the solid-lined triangle.

Answer 1

Refer to the edited figure.

Triangles ABC and A'B'C' are similar because of AAA.
Also,
$\frac{AB}{A'B'}= \frac{15}{5}=3 \\\\ \frac{AC}{A'C'}= \frac{12}{4}=3$

Therefore
ΔA'B'C' is 1/3 the size of ΔABC.
This means that the scale factor from ΔABC to ΔA'B'C' is a 3-factor reduction.

Answer:   reduction; one-third.
The dilation is a reduction.
The scale factor of the dilation is one-third.