This problem is about the sum of segments.
We know that
PR = 54 (the total length of the segment)
PQ = 4x + 7
QR = 5x + 11
By the segment addition postulate, we can say that
[tex]PR=PQ+QR[/tex]Replacing the given information, we have
[tex]54=4x+7+5x+11[/tex]Now, we solve for x
[tex]54-7-11=4x+5x\rightarrow9x=36[/tex]Then, we divide the equation by 9
[tex]\frac{9x}{9}=\frac{36}{9}\rightarrow x=4[/tex]