[ y - 4 = x - 8 ] is not the equation of the line that goes through
those two points. The first point (8, 4) is on the graph of that
equation, but the second point (0, 2) is not.
The slope/intercept equation of the line that passes through
both points (8, 4) and (0, 2) is
y = 1/4 x + 2 .
The slope/intercept form of [ y - 4 = x - 8 ] is
y = x - 4 .
