This math topic involves identifying line equations that have slopes perpendicular to the slopes of given lines represented in a graph. The problems test understanding of the concept of perpendicularity in slopes, specifically, knowing how to determine the opposite reciprocal of a given slope and then formulating it into a line equation in slope-intercept form. Each question provides a graph of a line and multiple choices of equations, where the task is to pick the one representing a perpendicular line.