To determine on which interval the function is decreasing, we would typically analyze the function's values or its derivative over the specified intervals. However, since I don't have access to the function or its graph, I can't provide a specific answer without more information.
If you have a graph or a data set, you can check for decreasing intervals by looking for sections where the function's values are lower at the end of the interval than at the beginning. You can also find the derivative of the function and see where it is negative.
Please provide more context, such as a function or a graph, and I'll be glad to help you analyze it!