The expression in the image is:

$9x - (4x + 3)$

To simplify this expression, follow these steps:

1. Distribute the negative sign across the terms inside the parentheses: $9x - 4x - 3$

2. Combine like terms (the terms involving $x$): $(9x - 4x) - 3 = 5x - 3$

So, the simplified expression is:

$5x - 3$

Would you like more details or have any questions?

Here are some related questions you might find helpful:

1. How do you distribute a negative sign over an expression in parentheses?
2. What are like terms in algebra, and how do you combine them?
3. Can you simplify the expression further if there were additional terms?
4. How would this change if the expression inside the parentheses were squared?
5. What happens if you have a variable inside the parentheses instead of a constant?

Tip: When simplifying expressions, always distribute signs carefully and combine like terms to avoid mistakes.