graphing

m = (y₂ - y₁) / (x₂ - x₁)

    = (-9 - 6) / (1 -(-4))

    = -15 / 5

slope is -3. 

(-4, 6)

y = mx + b

 

6 = -3(-4) + b

6 = 12 + b

b = -6

 

Which means the y intercept is (0, -6)

Slope of line   is        15 /-5 = -3

 

 

point slope form

 

y-6 = -3(x+4)

y = -3x -6                    b = -6