C is the circumcenter of APQR.
PC=3x+7, RC=5x-15, & QC=51-X
x=[?]

Answer:
x = 11
Step-by-step explanation:
C is the circumcenter of [tex]\triangle PQR[/tex]
[tex]\implies PC=QC=RC[/tex] (Radii of same circle)
[tex]\implies RC=QC[/tex]
[tex]\implies 5x-15=51-x[/tex]
[tex]\implies 5x +x=51+15[/tex]
[tex]\implies 6x =66[/tex]
[tex] \implies \: x = \frac{66}{6} \\ \\ \implies \: \huge \: \red{x = 11}[/tex]