y=mx+b
m is the slope
you need to get y on one side and all other numbers on the other
so here's the easiest way to do it:
just kinda take 4x (which is a positive number) and move it to the other side and change the sign. so then it turns into 6y=-4x+24 and then you divide both sides by 6 so then you get y=-4/6x+4 (4 over 6 like a fraction)
-4/6 is the slope