It's a good idea to be neat when doing algebra. If you are having difficulty adding or subtracting horizontally, try doing it vertically, lining up the like terms. A lot of math teachers will give at least partial credit if part of the equation is correct. Also, when your work is neat, you will be more apt to locate your errors prior to submitting your work. I demonstrate this neatness in the videos that I have posted on my page. Take a look at them.