Answer: 7
Work: So, the goal is to get z alone, so we are going to add 85 on both sides, cancelling on the side it's currently on. So, the new equation is going to be 25z = 175. Then, to get z even more lonely, we are going to divide 25 on both sides, and again cancelling it on the side it's currently on. So, the answer is z = 7. I hope this helps, and Happy Holidays! :)