What is the equation of the graphed linear model? y = x + scatter plot on a first quadrant coordinate grid. the horizontal axis is labeled variable a. the vertical axis is labeled variable b. points are plotted at (one, three), (two, ten), (three, six), (four, eight), (five, four), (six, nine), (seven, seven), (eight, eight), (nine, eleven). a line is drawn through point (one, three) and point (nine, eleven).