Respuesta :

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In a quadrilateral, all 4 of the angles must add up to 360. 
360 - 107 - 72 - 91 = x
253 - 72 - 91 = x
181-91 = x
90

Answer:

Step-by-step explanation:

360-107-72-91=x

253-72-91=x

181-91=x

your answer is 90