You can solve using substitution by having 3y + 5 = -4y + 5. Since they both equal x, you can have them equal each other. From there, you can add 4y to both sides, which will become 7y + 5 = 5. Then -5 from both sides, which is 7y = 0. That means y = 0. Plug in y to x = 3y + 5, and you get x = 5. Hope this helps!