The slope-intercept form of a line is
y = mx + b
If you write an equation in this form then m is the slope and b is the y-intercept. This is an extremely useful form if you are to sketch the graph since b tells you a point on the curve (0, b) and m. I am going to illustrate with a different line,
6x - 2y = 4.
The point intercept form is y = mx + b so I want y alone on the left of the equality so add -6x to both sides to obtain
6x - 2y - 6x = 4 - 6x
-2y = 4 - 6x
In the point slope form however the coefficient of y is 1 not -2, so divide both sides of the equation by -2.
-2y/-2 = (4 - 6x)/-2
y = 4/-2 - 6x/-2
y = -2 + 3x
y = 3x - 2