<u>Given</u>:
The two angles A and B are vertical angles.
The measure of ∠A is x and the measure of ∠B is 5x - 20.
We need to determine the measure of ∠A.
<u>Value of x:</u>
Since, the angles A and B are vertical angles and the vertical angles are always congruent.
Thus, we have;
Substituting the values, we have;
Adding both sides of the equation by 80, we have;
Thus, the value of x is 20.
<u>Measure of ∠A:</u>
The measure of ∠A can be determined by substituting x = 20 in the measure of angle A.
Thus, we get;
Thus, the measure of ∠A is 20°