Answer:
x = 20
Explanation:
The triangle shown is an equilateral triangle. An equilateral triangle has angles that are all the same. Therefore, the expression 4x-20 equals the value of the angle, which is 60 degrees. To find x, you just have to do some simple algebra.
4x - 20 = 60 ..... set the expression equal to 60, that's what the angle equals
4x = 80 .... add 20 to both sides
x = 20 .... divide both sides by 4, and you get your answer
Hope this helps! :)