The measure of Angle JHK is 25°.
What is the value of the angle in an Equilateral Triangle and Isosceles Triangle?
Equilateral triangle: All sides and angles are equal (60 degrees each).
Isosceles triangle: Two sides or angles are equal.
If GHI is an equilateral triangle, all its angles are equal to 60 degrees.
Hence,
7x - 31 = 60
Solving for x:
7x = 60 + 31
7x = 91
x = 91/7
x = 13 degrees
The measure of angle JHK is x + 12, so by substituting the value of x:
Angle JHK = 13 + 12
Angle JHK is 25°.