From the format of the equation, we know this graph is a straight line because it follows the form, y=mx+c. The coefficent of x (the number before x) describes the gradient of the straight line or m. This means that for every 1 unit you go across (in the x-axis), you go up (in the y-axis) 4 units. This number shows how steep the straight line is, the higher the number, the steeper the line. The number being added to the equation (+c) describes where the graph cuts the y-axis. This graph cuts the y-axis at +2.