For this case we have that by definition, the equation of a line of the slope-intersection form is given by:

Where:
m: It's the slope
b: It is the cut-off point with the y axis
While the point-slope equation of a line is given by:

Where:
m: It's the slope
It is a point through which the line passes
In this case we have a line through:
(8,4) and (0,2)
Therefore, its slope is:

Its point-slope equation is:

Then, we manipulate the expression to find the equation of the slope-intersection form:

Therefore, the cut-off point with the y-axis is 
ANswer:
