Answer:
x = 6
Explanation:
From the figure attached,
∠AFB ≅ ∠EFC [Vertically opposite angles]
Since, ∠AFB and ∠EFC are the central angles subtended by arcs EC and AB.
Therefore, (21x - 9) = m(∠EFC)
(21x - 9) = m∠EFD + m∠CFD
(21x - 9) = 90° + 27°
21x = 9 + 117
21x = 126
x = 6
Therefore, x = 6 will be the answer.