The measure of an interior angle of a regular n-sided polygon is calculated as $\frac{(n-2) \cdot 180^{\circ}}{n}$.
ABCDEFGHI is a regular nonagon, $P \in [FB]$, $|FD| = |FP|$, $\mathrm{m}(\widehat{\mathrm{APB}}) = x$.
According to the given information above, what is the measure of angle x in degrees?
A) 40
B) 45
C) 50
D) 55
E) 60