a) work out the size of angle x
b) give reasons for your answer

Answer:
angle B=100 degrees
vertically opposite angle
angle B +x= 180 degree
100-180=x
80 degree =x
Answer:
x = 80°
Step-by-step explanation:
GIVEN :-
TO FIND :-
PROCEDURE :-
∠CBD + ∠FBD = 180° (∵ ∠CBD & ∠FBD form a linear pair )
⇒ ∠FBD = 180° - 100° = 80°
Also,
∠FBD = ∠EFB (∵ Alternative Interior Angles are equal )
⇒ x = 80°