We can note that KN=JN, which implies that

then, by moving -3 to the right hand side, we get

then, x is given by

that is, x is equal to 3.
Now, from the congruent chord theorem, we know that if 2 chords of a circle are congruent (as in our case because LM=JK), then they are equidistant form the center of the circle. In other words,

Therefore, PS measure 5.5 units.