Mandy used the graph to write the equation of the line it represents. She took these steps. 1. y−intercept = (0, 2) 2. Slope = rise run = − 2 4 = − 1 2 3. Substituting values into y = mx + b y = x + On a coordinate plane, a line goes through points (0, 2) and (4, 0). The run = 4 and the rise = negative 2.