I am in 8th grade and algebra 2. I know exactly how to do what we learn, but I usually get things wrong because I do something simple such as adding wrong. Can anybody help?

Like Sincerity said ... Don't skip steps - practice - and review your work.

One way to review your work is to solve the problem a second time, using your first answer.

Example: If you are solving for X ... And you think the answer is 9 ... Replace X with 9 in the original problem, and see if it works out.