Given:
The equation of a line is

To find:
The slope and y-intercept of the line.
Solution:
We have,
...(i)
The slope intercept form of a line is
...(ii)
Where, m is the slope and b is the y-intercept.
On comparing (i) and (ii), we get

Slope of the line = 1
y-intercept of the line = -4
The coordinate form of y-intercept is (0,b). So, the y-intercept of the given line is (0,-4).
Therefore, the slope of the line is 1 and the y-intercept is (0,-4).
You can determine if points are collinear if they lie on the same line.
-23-4=-19
-19/9= -2.1111111
C=-2.11111