Answer
80
Work Step by Step
The single arcs tell us that $\angle FCA\cong\angle ECD$.
$m\angle FCA+m\angle ECD+m\angle FCE=180$
Substitute:
$50+50+m\angle FCE=180$
$100+m\angle FCE=180$
Subtract 100 from each side:
$100+m\angle FCE-100=180-100$
$m\angle FCE=80$
