Question 283476
The given formula is in slope-intercept form:  y = mx + b.
y = 3x -9
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The y-intercept is the point where x=0, so we see it is 'b', which equals -9, or the point (0,-9).
The x-intercept is the point where y=0, so we see it is x=3, or the point (3,0).
With two points you can draw a straight line.
.
{{{graph(500,500,-10,10,-10,10,3*x-9)}}}