The mathematical purpose of this lesson is to help students connect linear equations in two variables with the context the equation represents and the graph. Students compare multiple graphs and identify their slopes and intercepts. They also identify equivalent linear equations, some written in standard form and others in slope-intercept form. Students reason about the meaning of the slope and -intercept on a graph of a linear equation in the situation it represents, which provides an opportunity to think abstractly and quantitatively (MP2).