Answer:
75°
Step-by-step explanation:
Quadrilateral ABCD is a parallelogram.
[tex]\implies seg\: AB|| seg\: DC[/tex]
(Opposite sides of a parallelogram)
[tex]\implies m\angle A + m\angle B=180\degree[/tex]
(Interior angles on the same side of transversal)
[tex]\implies 105\degree + m\angle B=180\degree[/tex]
[tex]\implies m\angle B=180\degree-105\degree[/tex]
[tex]\implies m\angle B=75\degree[/tex]
[tex]seg \: AB || seg\: EF.....(Given)[/tex]
[tex]\implies m\angle B =m\angle BEF[/tex]
(Alternate angles)
[tex]\implies 75\degree =x [/tex]
[tex]\implies \huge\red{\boxed{x =75\degree}} [/tex]
