The expression \(3a + 6b\) can be simplified in a couple of ways, depending on what you are looking to do with it:
Factoring: You can factor out the greatest common factor. In this case, both terms have a common factor of 3.
\[ 3a + 6b = 3(a + 2b) \]
Evaluating for specific values: If you need to evaluate this expression for specific values of \(a\) and \(b\), you can simply substitute those values in.
If you have a specific question or context regarding this expression, please provide more details!