Question

1. a) 60° b) 99° c) 69° d) 116°

Explanation:

Step1: Use the property of consecutive interior angles

When two parallel lines are cut by a transversal, consecutive interior angles are supplementary (their sum is \(180^{\circ}\)).
Let the unknown angle be \(x\). We know that \(x + 81^{\circ}=180^{\circ}\)

Step2: Solve for \(x\)

Subtract \(81^{\circ}\) from both sides of the equation: \(x=180^{\circ}- 81^{\circ}\)
\(x = 99^{\circ}\)

Answer:

B. \(99^{\circ}\)