1. The expression given is $9b$. 2. This represents the product of the number 9 and the variable $b$. 3. In algebra, when a number is written directly next to a variable, it means multiplication. 4. So, $9b$ means $9 \times b$. 5. Without additional information about $b$, this is the simplest form of the expression. 6. If you know the value of $b$, you can substitute it and multiply by 9 to find the numerical value. Final answer: $9b$