If a, b, and c are three numbers, write the rule that gives the associative property of addition of three numbers.

Answer

To express the associative property of addition for three numbers \( a \), \( b \), and \( c \), we can write it as follows:

### Step-by-Step Solution:

1. **Understanding Associative Property**: The associative property states that when adding three or more numbers, the way in which the numbers are grouped does not change the sum. This means that the sum will be the same regardless of how the numbers are arranged.

2. **Writing the Rule**: For three numbers \( a \), \( b \), and \( c \), the associative property of addition can be expressed in two ways:
- First way: \((a + b) + c = a + (b + c)\)

3. **Explanation of the Rule**:
- In the first grouping, we add \( a \) and \( b \) first, and then add \( c \) to the result.
- In the second grouping, we add \( b \) and \( c \) first, and then add \( a \) to that result.
- Both methods will yield the same final sum.

4. **Example**: Let's take an example with specific numbers:
- Let \( a = 2 \), \( b = 3 \), and \( c = 5 \).
- Using the first grouping:
- \((2 + 3) + 5 = 5 + 5 = 10\)
- Using the second grouping:
- \(2 + (3 + 5) = 2 + 8 = 10\)
- Both methods give us the same result, which confirms the associative property.

### Final Rule:
Thus, the associative property of addition can be summarized as:
\[ (a + b) + c = a + (b + c) \]