In the figure below, angle y and angle x form vertical angles. Angle x forms a straight line with the 50° angle and the 40° angle. Write and solve an equation to determine the measure of angle y.
Since vertical angles are congruent, we have:
y = x
Since angle x forms a straight line with the 50° angle and the 40° angle, the sum of the angles is 180°. Therefore:
x + 50 + 40 = 180
x + 90 = 180
x = 90°
Therefore, the measure of angle y is:
y = x
y = 90°