<h3>
Answer: 17</h3>
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Explanation:
Refer to the remote interior angle theorem (some books call it the exterior angle theorem). That says we can add the two interior angles and the sum is the exterior angle that is not adjacent to either interior angle.
(interiorAngle1) + (interiorAngle2) = exterior angle
(5x) + (2x+6) = 8x-11
7x+6 = 8x-11
6+11 = 8x-7x
17 = x
x = 17
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Or the slightly longer method has you follow these steps:
y = missing interior angle in the upper right corner
The angle (8x-11) and angle y are supplementary
(8x-11) + (y) = 180
y = 180-(8x-11)
y = 180-8x+11
y = -8x+191
For any triangle, the three interior angles always add to 180
(angle1)+(angle2)+(angle3) = 180
(5x)+(2x+6)+(-8x+191) = 180
-x+197 = 180
-x = 180-197
-x = -17
x = 17
