2.)
0 = 6x + 3y +9
-3y = 6x + 3y - 3y +9

By isolating y we now have the equation in slope intercept form:

Where m = slope and b = y- intercept. Therefore, the slope is -2 and the y - intercept is -3.
4.)
Similarly, #4 is already in slope intercept form so we can solve it by inspection. So for #4 the slope is -1 and the y - intercept is 2.