are these triangles similar? if so, what postulate or theorem justifies that they are similar?

Answer:
Yes The triangles are similar by SAS Similarity Theorem
Step-by-step explanation:
we know that
Side-Angle-Side Similarity, states that If an angle of a triangle is congruent to an angle of another triangle and if the included sides of these angles are proportional, then the two triangles are similar
In this problem
Angle L is congruent with Angle Z
so
Verify if the included sides are proportional
so
[tex]\frac{LJ}{ZY}=\frac{KL}{XZ}[/tex]
substitute the values
[tex]\frac{3}{1.5}=\frac{4}{2}[/tex]
[tex]2=2[/tex] -----> is true
therefore
The triangles are similar by SAS