The problem asks for the difference between the expressions $(3x + 4x) + 2x$ and $3x + (4x + 2x)$.

Let's break down each expression:

1. Expression 1: $(3x + 4x) + 2x$

   Simplify the expression inside the parentheses: $3x + 4x = 7x$ Now, add the remaining $2x$: $7x + 2x = 9x$

2. Expression 2: $3x + (4x + 2x)$

   Simplify the expression inside the parentheses: $4x + 2x = 6x$ Now, add the remaining $3x$: $3x + 6x = 9x$

So, both expressions simplify to $9x$. Therefore, the difference between the two expressions is:

$9x - 9x = 0$

The correct answer is $0$.

Would you like any further details or explanations? Here are some related questions:

1. How do you combine like terms in algebraic expressions?
2. What is the distributive property, and how does it apply to these kinds of problems?
3. Can two different-looking algebraic expressions always simplify to the same expression?
4. What are the steps for simplifying complex algebraic expressions?
5. How can errors be avoided when simplifying expressions with multiple terms?

Tip: Always simplify expressions inside parentheses first before applying any other operations.