which equation can be solved to find x, the measure of BD in the diagram below?

The rule for the angle formed outside of circle by intersection show below is given by:
Angle formed outside=1/2(difference of intercepted arcs)
∠ACE=1/2(AE-BD)
∠ACE=53°
AE=233°
BD=x
Hence the formula for obtaining BD will be:
53=1/2(233-x)
The correct answer is A