The value of z is -10° if z= x-y.
What is parallelogram?
The parallelogram is the quadrilateral whose opposite sides are parallel and equal in length.
In a parallelogram, opposite angles are equal.
In a parallelogram, adjacent angles are sum to 180°.
Given in this question, angle ∠A = (x+30)°
angle ∠B= (x-30)°
angle ∠C= (y+20)°
As we know adjacent angles are sum to 180°
Here angles ∠A and ∠B are adjacent angles.
So ∠A + ∠B= 180°
⇒ (x+30)° + (x-30)° =180°
⇒2x=180°
⇒x= 180°/2= 90°
As we know opposite angles are equal.
Here angle A and C are equal.
∠A = ∠C
⇒(x+30)° = (y+20)°
⇒90°+30°= y+20°
⇒120°=y+20°
⇒y= 120°-20°
⇒y=100°
As given z= x-y
so z= 90°-100°
⇒z= -10°
Therefore the value of z is -10°.
Learn more about parallelogram
here: https://brainly.com/question/20526916
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