The function graphed is decreasing on the interval [-3, -2] U [ 2, 5]
How to find the interval
The interval when the graphed function is decreasing, is the points in the x-axis that marks where the line slopes downwards from left to right.
Examining the graph, this happens at two parts. A closer look at he graph shows that, the points marking this decrease are closed circles.
Closed circle means that the value at the point is included
Hence we have [-3, -2] then we have a stable form, before the decrease continues at [ 2, 5]