Answer:
2
Explanation:
In an arithmetic sequence, the common difference refers to the constant amount added or subtracted between consecutive terms. To find the common difference, we can subtract any term from the following term.
Let's subtract the second term (-13) from the first term (-15):
-13 - (-15) = -13 + 15 = 2
So, the common difference in the arithmetic sequence -15, -13, -11, ... is 2.