Distribute the 2 with the (3z-4) after distributing the 2, your answer would look like this: 5z-2=6z-8
then you would add 2 to both sides and your equation would look like this: 5z=6z-6
next you would subtract the 6z to both sides and your equation would look like this: -z=6
I think that is your answer sorry I tried.