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Supplementary angles, angles whose sum 180°
∠UTV + 90° = 180°
∠UTV = 180° - 90°
∠UTV = 90°
Exterior angle of a triangle, an angle formed from the extension of a side on the triangle and equals to the sum of the opposite interior angles
∠UVS = ∠UTV + ∠TUV
x + 8 = 90 + 64
x + 8 = 154
x + 8 - 8 = 154 - 8
x = 146
The value of x is 146