Answer:
Since the difference between each pair of consecutive terms is the same, the common difference (d) is -9.
Explanation:
In an arithmetic sequence, the common difference (d) is the constant value by which each term is obtained by adding or subtracting. Let's calculate it for the given sequence:
First, find the difference between the second and first terms:
6 - 15 = -9
Now, find the difference between the third and second terms:
-3 - 6 = -9
Since the difference between each pair of consecutive terms is the same, the common difference (d) is -9.