Answer:
x = 9.8
Step-by-step explanation:
(please refer to attached)
after labeling the picture with all the known information, we can see that 
OF = OR = Radius of the circle     -----(eq 1)
Consider triangle OFP,  by Pythagorean theorem, 
OF² = PF²+OP²
r² = 11.5² + 11²
r² = 253.25  -----(eq 2)
Consider triangle ORQ,  by Pythagorean theorem, 
OR² = RQ²+OQ²
r² = 12.5² + x²
r² = 156.25 + x²  ----(eq 3)
equating (eq 2) and (eq 3)
253.25 = 156.25 + x²    
x² = 253.25 - 156.25
x² = 97
x = √97
x = 9.8  (nearest tenth)