Question 67440
Well, you have the correct equation in the slope-intercept form: 
{{{y = (-3/4)x+8}}}
The slope is {{{-3/4}}} and, of course, slope is rise over run, so the rise is 3 and the run is 4.
The question of which part of the slope is negative is really irrelevant. The entire slope is negative which means that the line leans to the left.
One way to look at it is in drawing the line so that is has the correct slope, you would go up (rise) 3 units on the graph and then go left (run) -4 units.  Why left and not right? Well, because the slope is negative (left-leaning) and not positive (right-leaning).