In the figure, lines l and m are parallel, y = 20, and z = 60. What is the value of x?

Explanation

The correct answer is Choice B: 100. The parallel lines and the transversal create corresponding angles, so a = y = 20°. In the triangle, the angles a, x, and z must sum to 180°. Given a = 20° and z = 60°, we solve for x: 20 + x + 60 = 180, resulting in x = 100°. Other options result from common misconceptions about angle relationships in triangles and parallel line properties.