1) Since Q is the midpoint of PR, according to the definition of midpoint. Then the segments PQ = QR, and they both are congruent
Let's first find PQ, s
PR = PQ+QR
5x+4=PQ +6x-54
5x+4-6x+54=PQ
-x+58=PQ
PQ =-x+58
2) PQ=QR
-x+58=6x-54
58+54=6x+x
112=7x
x=16
3) Plugging into the x, the value found.
PQ =-x+58
PQ =-16+58
PQ =42º