Question 272054
m=(y2-y1)/(x2-x1)
(2,4),(x,8)m=-2
-2=(8-4)/(x-2)
-2=4/(x-2) cross multiply
-2(x-2)=4
-2x+4=4
-2x=4-4
-2x=0
x=0 
(2,4),(0,8) ans.
4=-2*2+b
4=-4+b
b=4+4+8 the Y intercept.
y=-2x+8
{{{ graph( 300, 200, -6, 5, -10, 10, -2x +8) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, -2x +8)