Answer:
Let us set up a ratio to find the relationship between side lengths of the two triangles.
25:10
5:2
We can divide both sides by two, but there's no need as the smaller triangle has multiples of two.
So, if XZ is 6, let's place it into the ratio and find what "x" is.
5(3) : 2(3)
15 : 6
x = 15