Lines: y = mx+c Move the sliders and see how the line changes. Now you can control both the the gradient and the position of the line. What you should understand Equations of the form y = mx+c are called linear equations. When you plot values of these equations on a graph the points will lie on a straight line. This straight line has "y-intercept" c and gradient m, where m = rise/step. When looking at a linear graph, if you can figure out the gradient and the y-intercept then you can say what the equation of the line is. controls