Answer:
x = -11
Step-by-step explanation:
Let the Triangle be named 'ABC'
In Triangle ABC,
∠A = x + 51
∠B = 80 (Intersecting lines, Vertically opposite Angles)
∠C = 60 (Intersecting lines, Vertically opposite Angles)
∠A + ∠B + ∠C = 180 (Sum of angles of Triangle = 180)
x + 51 + 80 + 60 = 180
=> x + 191 = 180
=> x = 180 - 191
=> x = -11
