You can put this solution on YOUR website! Y=mX+b
-4=-1/2*7+b
-4=-7/2+b
b=-4+7/2
b=-8/2+7/2
b=-1/2 ans. for the Y intercept.
y=-x/2-1/2 is the line equation through (7,-4) with a slope=-1/2. (graph 300x200 pixels, x from -6 to 8, y from -10 to 10, -x/2 -1/2).