Answer:
120°
Step-by-step explanation:
ABCD is cyclic quadrilateral, which the sum of opposite angles = 180°. Therefore:
∠ADC + ∠ ABC = 180°
∠ABC = 180° - ∠ADC
∠ABC and ∠CBE are supplementary angles, which the sum of the 2 angles = 180°. Therefore:
∠ABC + ∠CBE = 180°
(180° - ∠ADC) + x = 180°
x = ∠ADC
= 120°
