The expression given in the image is:

$5x + 9 + 4x + 2$

To simplify this expression, we need to identify and combine the like terms. Like terms are terms that have the same variable part (or no variable, in the case of constants).

Steps:

1. Combine the terms with $x$: $5x + 4x = 9x$
2. Combine the constant terms: $9 + 2 = 11$

Now, putting these together:

$9x + 11$

So, the simplified expression is: $9x + 11$

Would you like more details or have any questions?

Here are 5 related questions:

1. What are like terms in an algebraic expression?
2. How do you simplify expressions involving multiple variables?
3. Can you explain the process of distributing terms in algebraic expressions?
4. What happens when an expression has no like terms?
5. How do you handle subtraction when simplifying algebraic expressions?

Tip: Always combine like terms first when simplifying expressions to avoid errors!