Find the Missing Angle

In the figure below, lines a and b are parallel, and lines c and d are parallel.
What is the measure of ∠x ?

A.)  75°
B.)  95°
C.)  100°
D..)  105°
E.)  113°

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Just one way to look at it is:

The missing angle in the triangle containing the angles of 30° and 75° is equal to 75°,
since angles of a triangle add up to 180°

Therefore, since lines a and b are parallel, and lines c and d are also parallel,
the angle to the right of ∠x is also equal to 75°.  A parallelogram is formed, where opposite angles are equal.

Angles in a straight line add up to 180°.  Since the angle to the right of ∠x is 75°,
then ∠x is equal to 105°.

D.)  105°

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