The equation is y = -1/5x + -42/5
The equation for slope is
y1 - y2
_________ = m
x1 - x2
-6 - -9 = 3
_________ = 3/-15 = -1/5
-12 - 3 = -15
m = -1/5
The equation for a line is y = mx + b.
m is -1/5
y = -1/5x + b
Plug in any point of the line into x and y.
-9 = -1/5(3) + b
-9 = -3/5 + b
-45/5 = -3/5 + b
-42/5 = b
y = -1/5x + -42/5
