Question

One angle of an equilateral triangle measures (4x-20)°. What is the value of x?

Answer 1

An equilateral triangle has degrees of 60-60-60
solving the equation, you will find 4x=80 and x=20

Answer 2

All triangles have a total degree number of 180. Each angle of an equilateral triangle is 60.
This is the work you do:
4x-20=60
4x=80
x=20