The slope of the line is 4
The point slope form of the line can be written as (y - 8) = 4(x - 9)
The slope intercept form of the line is y = 4x - 28
In order to find the slope you will need to use the formula for slope. It is included below.
m(slope) = (y2 - y1)/(x2 - x1)
m = (8 - -12)/(9 - 4)
m = (8 + 12)/(9 - 4)
m = 20/5
m = 4
Now that we have the slope, we can plug it into point slope form along with one of the points.
(y - y1) = m(x - x1)
(y - 8) = 4(x - 9)
Now to get to the slope-intercept form of the line, we can simply manipulate the point-slope form until it is in y = mx + b
(y - 8) = 4(x - 9) ----> Distribute the 4
y - 8 = 4x - 36 -----> Add 8 to both sides
y = 4x - 28