<u>Given</u>:
The given triangle has three equal sides. Thus, the given triangle is an equilateral triangle.
The measure of one angle is (4x - 20)°
Since, it is an equilateral triangle, then all the three sides will be equal.
We need to determine the value of x.
<u>Value of x:</u>
The value of x can be determined using the triangle sum property.
Thus, we have;
Simplifying, we have;
Adding the like terms, we have;
Thus, the value of x is 20