Question 931376
First graph the line {{{x-y=8}}}
{{{y=x-8}}}
Here the slope is {{{m=1}}} and the y-intercept is {{{y=-8}}}.
So one point is (0,-8).
Since the slope is 1, change in y over change in x is one. 
So to get another point add (1,1) to the intercept.
(0,-8)+(1,1)=(1,-7)
Now that you have two points, you can plot the line.
{{{drawing(300,300,-10,10,-10,10,grid(1),circle(0,-8,0.3),circle(1,-7,0.3),graph(300,300,-10,10,-10,10,x-8))}}}
OK, so now pick a point not on the line. (0,0) is convenient.
Test the inequality.
If the inequality is true, shade the region containing (0,0).
If the inequality is false, shade the region that doesn't contain (0,0).
{{{x-y>8}}}
{{{0-0>8}}}
{{{0>8}}}
False, so shade the region not containing (0,0).
{{{drawing(300,300,-10,10,-10,10,grid(1),circle(0,-8,0.3),circle(1,-7,0.3),graph(300,300,-10,10,-10,10,y<x-8))}}}