Answer
The scale factor is $\frac{2}{3}$ or $2:3$.
Work Step by Step
To find the scale factor of two similar polygons, we find the ratio of the measures of corresponding sides.
Let's use sides that we know the definite measures of. This means we will use the corresponding sides $TR$ and $EZ$:
$\frac{TR}{EZ} = \frac{4}{6}$
Divide both the numerator and denominator by their greatest common factor, $2$:
$\frac{TR}{EZ} = \frac{2}{3}$
The scale factor is $\frac{2}{3}$ or $2:3$.