We are given two triangles. We notice that each corresponding angle is equal, therefore, by Angle Angle Angle (AAA) theorem the triangles are similar. This means that each corresponding side is at the same ratio. That ratio is called the similarity ratio and it is obtained by finding the quotient between any two corresponding sides, like this:
[tex]r=\frac{DF}{VW}=\frac{DE}{VX}=\frac{FE}{WX}[/tex]Where "r" is the similarity ratio. Now, we substitute the sides:
[tex]r=\frac{4}{2}=\frac{4}{2}=\frac{2}{1}=2[/tex]Therefore, the similarity ratio is 2.