<h3>Answer: Angle 1 is 80 degrees</h3>
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Explanation:
See the diagram below. I've extended one of the rays to form a full line. This is shown in red. The alternate interior angles 60 and x are congruent due to the parallel lines, so x = 60.
We can then find angle y
x+y+20 = 180 ... angles of a triangle add to 180
60+y+20 = 180
y+80 = 180
y = 180-80
y = 100
Use this to find z
y+z = 180
100+z = 180
z = 180-100
z = 80
Or you could use the remote interior angle theorem
x+20 = z
60+20 = z
80 = z
z = 80
