The expression $x + x$ can be simplified by combining the like terms. Since both terms are $x$, the sum is:

$x + x = 2x$

Would you like further explanation on this?

Here are 5 related questions you might find useful:

1. What happens when we combine $3x + 2x$?
2. How do you simplify algebraic expressions?
3. What is the difference between combining like terms and solving equations?
4. How do you solve $2x = 10$ for $x$?
5. Can you apply the distributive property to expressions like $x + x$?

Tip: Always look for like terms in an algebraic expression to simplify it before solving.