Answer:
x=90 degrees
Step-by-step explanation:
The sum of the 4 angles of a quadrilateral add to 360 degrees
Add the 4 angles
72+107+x+91 = 360
Combining like terms
270 +x = 360
Subtract 270 from each side
270+x-270 = 360-270
x = 90
The unknown angle is 90
