Start the line at 3 on the y-axis (vertical). then go down two boxes and to the right three & make a mark at that point. keep going down two and over three until the end of the graph. then just connect the marks.
The slope-intercept form is:
y = mx + b
where m = slope, and b = y-intercept.
You need a slope of 1, so m = 1.
You need a y-intercept of -1, so b = -1.
Replace m with 1 and b with -1 in the slope intercept form to get
y = 1x + (-1)
which simplifies to
y = x - 1
