To simplify the expression $7x + 3 - 5x - 9$:

1. Combine like terms:
   • Combine the terms involving $x$: $7x - 5x = 2x$
   • Combine the constants: $3 - 9 = -6$

So, the simplified expression is: $2x - 6$

Would you like further details or have any questions?

Here are 5 related questions you might consider:

1. How do you solve an equation like $7x + 3 = 5x + 9$?
2. How can you factor an expression like $2x - 6$?
3. What are like terms, and how do you identify them in algebraic expressions?
4. How do you solve equations with variables on both sides?
5. How do you simplify more complex algebraic expressions?

Tip: Always group and simplify like terms first to make solving algebraic expressions easier.