To simplify the expression $5x + 2 + 7x + 4$, follow these steps:

1. Combine like terms involving $x$: $5x + 7x = 12x$

2. Combine the constant terms: $2 + 4 = 6$

So, the simplified expression is: $12x + 6$

Would you like further details or have any questions?

Here are 8 related questions you might find useful:

1. How do you simplify algebraic expressions with multiple terms?
2. What is the distributive property, and how does it apply to simplifying expressions?
3. How do you solve linear equations for a specific variable?
4. Can you solve the equation $12x + 6 = 0$?
5. How do you factor the expression $12x + 6$?
6. What is the difference between like and unlike terms in algebra?
7. How do you solve equations that involve combining like terms on both sides?
8. How do you solve systems of linear equations?

Tip: Always combine like terms first when simplifying an expression.