Answer:
∠ GHI = 17°
Explanation:
the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ HIJ is an exterior angle of the triangle , then
∠ HJI = ∠ GHI + ∠ IGH , that is
7x - 18 = 2x - 3 + 2x + 15
7x - 18 = 4x + 12 ( subtract 4x from both sides )
3x - 18 = 12 ( add 18 to both sides )
3x = 30 ( divide both sides by 3 )
x = 10
Then
∠ GHI = 2x - 3 = 2(10) - 3 = 20 - 3 = 17°