Answer:
The value of x is 40°
Explanation:
The triangle described in the text of the question is shown in the image attached.
Note the angles x and 4x-20 are supplementary since they form a line. Thus:
x + 4x - 20 = 180
Simplifying:
5x - 20 = 180
Adding 20:
5x = 200
Solving:
x = 200/5 = 40
The value of x is 40°