Explanation:
come on !
how do you create a line ?
you mark 2 points, take a ruler and draw a line through both points (and extend the line beyond the points as far as the chart goes).
how do you find points ?
you think about a nice value for x (really, any value on the x-axis of the chart is OK) and then calculate y.
you mark the point at this x, y coordinates.
you know, the x-axis is the horizontal coordinate line, and the y-axis is the vertical coordinate line.
so, I would pick x =0. that gives us y = 0 + 0.5 = 0.5.
and maybe x = 2. that gives us y = 2 + 0.5 = 2.5
so, you have (0, 0.5) and (2, 2.5) as points.
and then simply do as described above.