The objective in this question is to get rid of the 8 on the left. When you do that you will have all the numbers on the right, and all the variables on the left. The equation will be solved. If the solution is not what you want, then be a little bit more careful about how you post a question.
Add 8 to both sides.
n +8 - 8 = - 10 - 8
n = - 18 Think money when you do the question. If you owe 10 dollars and you spend 8 more, you go more and more in debt. That's the same way with this question. You go more and more negative.