The applet opens with the lines 3x + 2y = 12 and 2x + 3y = 4 drawn. The red line is given by ax + by = c. You can change the line in the Input Field. For example, try typing in a = -1 and press the ENTER key. Similarly the blue line 2x + 3y = 4 is given by the equation px + qy = r. These numbers can also be changed by you. You may need to use the zoom tools or move the drawing pad to view the point of intersection.