There are 360° in a complete turn.
There are 180° in half a turn (a straight line).
Find the size of angle z:
There are 360° in a complete turn, so z + 40 + 110 + 130 = 360
z + 280 = 360
z = 80°
What is the size of angle p?
The angles on a straight line add up to 180°, so p + 140 = 180.
p = 40°
The angles in a triangle add up to 180°
The angles in a quadrilateral add up to 360°.
This works for any quadrilateral. Again, you can try this for yourself with a piece of paper!
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