the slope is -8/3 i got this by first subtracting 8z from both sides to get 3y by itself so the new equation was 3y=9-8z then to isolate y you need to divide everything by 3 so divide 3y by 3 which cancels out and leaves you with y then divide 9 by 3 which is 3 and divide -8 by 3 and you cannot do that do you leave it in fraction form which is -8/3z so your new equation is y=3-8/3z
hope this helps