11, 12, 14-17, 20.
This is still review from last week.
You can use notes, homework and examples in the book on page 202 and 203.
You are putting like terms together to simplify expressions.
First, if there is no multiplication, get one sign for every term.
Second, what terms can go together.
Third, decide if you are adding or subtracting terms that are "like".
Do not force terms together that are not the same.
Lastly, some examples (at least one) may require you to plug in a value for the variable.
If so, plug in the value and simplify the expression using PEMDAS.