Answer: 126 degrees
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Explanation:
Since L and M are parallel lines, this means x+y = 180 due to the same side interior angles theorem. Some books refer to these angles as consecutive interior angles.
If x+y = 180, then y = 180-x.
Plug this into the equation your teacher gave you
x/y = 3/7
x/(180-x) = 3/7
7x = 3(180-x) ... cross multiply
7x = 540 - 3x
7x+3x = 540
10x = 540
x = 540/10
x = 54
Use this to find y
y = 180-x
y = 180-54
y = 126
Then notice how x/y = 54/126 = 3/7, which helps confirm we have the correct x and y values.
Divide both parts of the first fraction by 18 to fully reduce.
Now because angles y and z are alternate exterior angles, this must mean z = y = 126 degrees
