two parallel lines are crossed by a transversal. what is the value of y? y = 40 y = 80 y = 100 y = 120

Explanation:

Step1: Recall angle - relationship

When two parallel lines are cut by a transversal, corresponding angles are equal and adjacent angles on a straight - line are supplementary (sum to 180°). The 80° angle and the angle adjacent to (y) are corresponding angles, so the angle adjacent to (y) is 80°.

Step2: Use supplementary - angle property

Since the angle adjacent to (y) and (y) are on a straight - line, we know that (y + 80^{\circ}=180^{\circ}).

Step3: Solve for (y)

Subtract 80° from both sides of the equation: (y=180^{\circ}-80^{\circ}).

Answer:

(y = 100)