Given the following points
(8, 4 ) and (20, -4)
Step 1: Find the slope of the two lines
Slope = rise / run
Where rise = y2 - y1 , and run = x2 - x1
Slope = y2 - y1 / x2 - x1
According to the points, let x1 = 8, y1 = 4, x2 = 20 and y2 = -4
Slope = -4 - 4 / 20 - 8
Slope = -8 / 12
Slope = -8/12
Slope = -2/3
The slope - intercept equation is given as
(y - y1) = m(x - x1)
x1 = 8, and y1 = 4
(y - 4) = -2/3(x - 8)
y - 4 = -2/3x + 2 x 8 / 3
y - 4 = -2/3x + 16/3
Isolate y
y = -2/3x + 16/3 + 4
Find the common denominator
y = -2x + 1