this week we learned chapter7: how to simplify, multiply and divide, add and substruct rational expressions. I learned it when I was in China so it was not hard for me to understand. All I need to do was to review and to memorize the math languages.
For example,

To solve this question, first, we need to find the lowest common denominator, which is 9x; then multiply 3 to both the top and bottom of the first equation. So it becomes:

We can add the tops together after this step, so we get:

Problem solved.
If the answer is reducible, we must finish the reducing step too.