Question 346562
{{{drawing(300,300,-5,10,-10,5,circle(-2,3,0.3),circle(0,1,0.3),circle(3,-2,0.3),circle(7,-6,0.3),grid(1),graph(300,300,-5,10,-10,5,0))}}}
Use the first and last point to calculate the slope (although you could use any two points). 
{{{m=(y[2]-y[1])/(x[2]-x[1])=(-6-3)/(7-(-2))=-9/9=-1}}}
The intercept is one of the points:({{{0}}},{{{1}}})
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{{{highlight(y=-x+1)}}}
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{{{drawing(300,300,-5,10,-10,5,circle(-2,3,0.3),circle(0,1,0.3),circle(3,-2,0.3),circle(7,-6,0.3),grid(1),graph(300,300,-5,10,-10,5,-x+1))}}}