When you graph linear equations, you may notice that some lines tilt up as they go from left to right and some lines tilt down. Some lines are very steep and some lines are flatter. What determines wh...When you graph linear equations, you may notice that some lines tilt up as they go from left to right and some lines tilt down. Some lines are very steep and some lines are flatter. What determines whether a line tilts up or down or if it is steep or flat? In mathematics, the ‘tilt’ of a line is called the slope of the line. The concept of slope has many applications in the real world: the pitch of a roof, grade of a highway, and a ramp for a wheelchair are some examples.