please i know the awnser is 60 but i cant explain it

Answer:
a) 60 degrees
Step-by-step explanation:
b) The triangle shown is an equilateral triangle as all the sides are the same. This means that all the angles are the same as well.
Angles in a triangle add up to 180 degrees. There are 3 angles. Each angle is 60 degrees.
Angle x is an exterior corresponding angle and hence, that is why x = 60 degrees.
Answer:
All of the measures of the interior angles of an equilateral triangle are 60°. Because x and 60° are alternate interior angles of parallel lines, this means that they are equal, therefore x = 60°.