This would be unlike our typical functions, which are of the form y = mx + b (linear), or y = x2 + bx + c. That is you are graphing the value y in terms of x. Here, if you set up your graph, you might put y on the horizontal axis and D on the vertical axis. That would be D in terms of y. You might have D = 12y - 3y2 for example. Make sure that D is the variable on one side and y values on the other.