Fill in the blanks and state the property used.
`(-946)+(-209)="_______"+(-946)`

Options

A. `(-209)`
Property used : distributive property
B. `(-229)`
Property used : associative property
C. `(209)`
Property used : Commutative property
D. `(-209)`
Property used : Commutative property

Answer

To solve the question `(-946) + (-209) = "_______" + (-946)`, we will use the commutative property of addition. This property states that the order in which two numbers are added does not change the sum.

### Step-by-Step Solution:

1. **Identify the Terms**: In the expression `(-946) + (-209)`, we have two terms: `-946` and `-209`.

2. **Apply the Commutative Property**: According to the commutative property, we can switch the order of addition. Therefore, we can write:
\[ (-946) + (-209) = (-209) + (-946) \]

3. **Fill in the Blank**: Now, we need to express the original equation in the form `(-209) + (-946)`. Thus, we can fill in the blank:
\[ (-946) + (-209) = (-209) + (-946) \]
Hence, the blank should be filled with `-209`.

4. **Final Statement**: Therefore, the complete equation is:
\[ (-946) + (-209) = (-209) + (-946) \]
The property used here is the **Commutative Property of Addition**.

### Final Answer:
The blank is filled with `-209`, and the property used is the **Commutative Property of Addition**.