Fill in the blanks.
In the algebraic expression `x+3, 3` is added to ____________ .

Answer

To solve the question, we need to understand the components of the algebraic expression given, which is \( x + 3 \).

1. **Identify the expression**: The expression is \( x + 3 \). Here, \( x \) is a variable, and \( 3 \) is a constant.

2. **Analyze the operation**: The expression indicates that \( 3 \) is being added to something. In this case, it is added to \( x \).

3. **Fill in the blank**: Since \( 3 \) is added to \( x \), we can fill in the blank with \( x \).

Thus, the complete statement is: "In the algebraic expression \( x + 3 \), \( 3 \) is added to \( x \)."

### Final Answer:
In the algebraic expression \( x + 3 \), \( 3 \) is added to **\( x \)**.