Answer:
x = 60
Explanation:
Vertical opposite angles are formed when two straight lines intersect each other.
Given that AD and CD are two straight lines intersecting at O, the two vertical opposite formed are, ∠AOD and ∠COB. Therefore:
∠AOD = ∠COB (Vertical opposite angles are congruent)
∠AOE = 90° (right angle)
∠DOE = x
∠COF = 30°
∠BOF = 2x
m∠AOE + m∠DOE = m∠AOD (angle addition postulate)
90 + x = ∠AOD (Substitution)
m∠COF + m∠BOF = m∠COB (Angle addition postulate)
30 + 2x = ∠COB
m∠AOD = m∠COB (vertical opposite angles)
90 + x = 30 + 2x (Substitution)
Collect like terms
90 - 30 = 2x - x
60 = x
x = 60