In a linear pair, the measures of two angles sum to 180 degrees. Given m<1 = 5x + 9 and m<2 = 3x + 11, the equation to solve is 5x + 9 + 3x + 11 = 180. Solving for x allows for the determination of the individual angle measures. Understanding the concept of a linear pair is crucial for setting up the equation correctly. The problem emphasizes the importance of recognizing angle relationships in geometry.