Let the exterior angle be y.
We know that the exterior angle is the sum of opposite two interior angles.
Therefore, y = 3x + 90 --- (1)
Also, y and 5x - 6 are linear pair.
Therefore, y + (5x - 6) = 180
Substituting y = 3x + 90 from (1), we get,
(3x + 90) + (5x - 6) = 180
8x + 84 = 180
8x = 180 - 84 = 96
x = 12 degrees
Hence, exterior angle y = 3(12) + 90 = 126 degrees.
