In the same circle two minor arcs are congruent if and only if their corresponding chords are congruent.
We know that chords LM and PM are congruent. By the theorem the corresponding minor arcs are also congruent.
mLM=mPM
⇕
mLM=x^(∘)
By the Arc Addition Postulate and feature of the circle all central angles sum up to 360^(∘).
106^(∘)+x^(∘)+x^(∘)=360^(∘)
Let's solve this equation for x.