Let’s start from the top: Find corresponding sides.
Seg. AB is corresponding to Seg. JK (we won’t need it to solve)
Seg. BC is corresponding to Seg. KL
Seg. CA is corresponding to Seg. LJ.
Now to find the scale factor. Since the CA-LJ relation is the only one where we know both sides, we’ll use that as the reference point.
25/15 is the same as 5/3, which is the scale factor between the two triangles.
This sets up this equation:
2x+5 = 9(5/3)
2x+5 = 45/3 (multiply)
2x+5 = 15 (simplify)
2x = 10 (subtraction PoE)
x = 5 (division PoE)
X is 5 if triangle ABC is similar to triangle JKL.