Respuesta :

Answer:

x = 9

Step-by-step explanation:

The alternate interior angles theorem tells us that these two quantities must be the same.

Therefore,

x + 18 = 4x - 9

x + 18 + 9 = 4x

x + 27 = 4x

27 = 4x - x

27 = 3x

x = 9

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